Large Plywood Tank

[tomason]

I'd like to build a 96"x24.5"x32" tank out of plywood, and I've been trying to find answers to the following questions all over the internet, but I just haven't had any luck yet:

1. I've found 2 documented cases of >400 gallons tanks being build using the GARF plans, however GARF's site recommends not building a tank longer than 48" when the height is more than 24". Both of those guys did it anyway and it held water long enough for them to get them all set up and stocked and take pictures of it. Is that a smart thing to do long-term?

2. The GARF plans call for a very large (12") plywood brace across the top. A tank 8' long would probably need 3 or so of them. That would really screw up the reef lighting! Could those braces be made of acrylic instead? Could they just be screwed on like the plywood ones?

3. If I can't use acrylic for the braces, could I compensate by making the hood hold it together? Or how about a frame around the top made of 2x4's?

4. Should I just bite the bullet and make it out of acrylic for a lot more? That's what I was originally planning before I realized there's only going to be 1 viewable side where my wife wants to put it.

Thank you!

-Tom

[wiliiam]

I would think that if you did a 3 " lip out of plywood you could cement a couple of strips of acrylic under the lip w/ weldon 40

[tomason]

So would weldon 40 really bond with the epoxy-painted plywood?

Or what about DOW 795 silicone as the bonding agent plus screws through the plywood lip into the acrylic brace?

What thickness of acrylic should I use?

Thank you!

-Tom

[jayo]

I can't help you at all, but here is an article about a really really big plywood tank:

http://www.cichlid-forum.com/articles/diy_1700g_tank_1.php

It is way cool enough in its own right even if it doesn't help you at all!!!

jayo

[tomason]

Wow! That was a cool article!

Another question: Would there be any problem with finishing the outside of the tank the same as the hood and canopy? I don't see why not, since the epoxy paint keeps the plywood dry anyway. I just thought I'd ask just in case.

-Tom

[tomason]

It's been a few more days now, and I've found a lot more information out there. Plywood tanks seem to be extremely popular with the cichlid crowd!

I'll post the most common methods for sealing the plywood in case any of you might have some insight into them:

1. Coat the interior plywood surfaces with 2-part epoxy paint and put a bead of silicone along all the inside edges

2. Coat the inside with just epoxy resin

3. Go all out and fiberglass the inside and then apply a couple coats of 2-part of epoxy paint to finish it

4. Just put fiberglass tape along the inside edges and seal the rest of the wood with just the epoxy resin

#1 scares me, but people have done it successfully.

#2 is better.

#3 is definitely over-kill and puts the cost of the tank up past acrylic.

#4 seems like a good balance of strength reinforcement for the seams, and the epoxy resin is definitely waterproof. After all, that's what boat-makers use for the hulls.

The plywood is extremely strong - stronger than glass and acrylic. It provides all the necessary structural support. The sealant just has provide a water barrier and not crack if flexed too much and then leak. That's where the fiberglass along the inside edges comes in. It greatly increases the tensile strength of the waterproofing where it needs it.

I was hoping to be able to afford a Starphire glass panel because I would be saving so much on the rest of the tank, but alas it's WAY more expensive than I could have imagined. The cost of the glass using regular 1/2" tempered plate glass is $262. The Starphire glass is $727!!!!!!!! That's more than all of the acrylic would be to make the whole thing!

There's so much information among the reef websites about acrylic tank construction, and even some on glass tank construction. However, there's hardly anything on plywood tanks. I think that's interesting. Perhaps it has something to do with the tank cost being so much less (relatively speaking) for a reef system than it is for the freshwater folks. Who knows!

-Tom

[gev]

Originally posted by tomason
I'd like to build a 96"x24.5"x32" tank out of plywood, and I've been trying to find answers to the following questions all over the internet, but I just haven't had any luck yet:

2. The GARF plans call for a very large (12") plywood brace across the top. A tank 8' long would probably need 3 or so of them. That would really screw up the reef lighting! Could those braces be made of acrylic instead? Could they just be screwed on like the plywood ones?

3. If I can't use acrylic for the braces, could I compensate by making the hood hold it together? Or how about a frame around the top made of 2x4's?


Here's (http://reefcentral.com/forums/showthread.php?s=&threadid=87733) a thread in which someone used threaded rod for bracing. It will not interfere with your lighting.

[MarkS]

Originally posted by tomason
I'd like to build a 96"x24.5"x32" tank out of plywood, and I've been trying to find answers to the following questions all over the internet, but I just haven't had any luck yet:

1. I've found 2 documented cases of >400 gallons tanks being build using the GARF plans, however GARF's site recommends not building a tank longer than 48" when the height is more than 24". Both of those guys did it anyway and it held water long enough for them to get them all set up and stocked and take pictures of it. Is that a smart thing to do long-term?

2. The GARF plans call for a very large (12") plywood brace across the top. A tank 8' long would probably need 3 or so of them. That would really screw up the reef lighting! Could those braces be made of acrylic instead? Could they just be screwed on like the plywood ones?

3. If I can't use acrylic for the braces, could I compensate by making the hood hold it together? Or how about a frame around the top made of 2x4's?

4. Should I just bite the bullet and make it out of acrylic for a lot more? That's what I was originally planning before I realized there's only going to be 1 viewable side where my wife wants to put it.

Thank you!

-Tom

I really am tired of GARF's misinformation...

1.) I have seen a freshwater tank with the dimensions of 96" x 48" x 48". The guy underbuilt the tank. It was pretty scary, but held water. If you are really concerned, just laminate two sheets of plywood together.

2.) Not nescessay. Look at David Grigor's (http://www.thefloodedbasement.com) web page. Also look at the thread that gev posted. It has pics of David's tank starting at page two. He used a very small Euro brace along with threaded rods. You could even use just the rods.

3.) You could do that, but see #2 again. I would recommend the rods.

4.) I think it is more fun to do as you are doing it. Unfortunately, I never finished the wooden tank I was going to build. I have since re-designed and am planning on making it bigger... A LOT bigger. Wood is much more forgiving than acrylic and easier to work with, not to mention cheaper.

Mark

[GARFVolunteer]

Originally posted by MarkS
I really am tired of GARF's misinformation...

1.) I have seen a freshwater tank with the dimensions of 96" x 48" x 48". The guy underbuilt the tank. It was pretty scary, but held water. If you are really concerned, just laminate two sheets of plywood together.

How is a recommendation misinformation?

When I designed the calculator I was assuming people with common sense would be using it. There were people that built the tank like the one you mentioned and ended up with a livingroom full of water. We decided to temporarily place limits on the size of tank the calculator will design until I had time to fix it. Since I am no longer volunteer at GARF, it will probably stay the way it is...

Thanks

Scott

[jjmg]

I don't think there is anything wrong with the GARF plans. If I was going to go bigger I would just modify them for the extra size. Isn't that what DIY is all about...get a good idea from someone or something else and make it your own?

The threaded rods make a lot of sense.

[MarkS]

Common sense has nothing to do with it. Plywood is very strong and if constructed right, there is no reason why someone could not go taller than 24" if they wanted too. I am planning a 96" long x 96" deep x 48" tall aquarium out of plywood. It would only have one viewing panel and would be made for a future in wall tank. All sides, including the bottom, would be double laminated out of 3/4" plywood. Epoxy would be used to laminte the wood. The front glass would be 1" thick. For the front, there would be two 1/2" pieces sanwiched between two 3/4" pieces. The 1/2" pieces would be inset about 2" so the glass seats down between the 3/4" pieces. I am very comfortable with this design and have no fear of it leaking.

I recommend that he gules the edges with Professional Strength Liquid Nails. Use 4" screws every 4". I'd definitely go with David's method of using threaded rods. It would probably be best to use 4 or five.

[tomason]

Hey, thanks for the info! I hadn't seen that one gev posted before.

GARFVolunteer, that's also information I was looking for!!! I mentioned in my first post that the tanks lasted long enough to post them on the internet, but I didn't know if they were still working. :)

So it seems that as long as the wooden structure is sound, epoxy paint is just fine. I've been spending most of my time researching ways to seal it, when I guess I should have been researching the rigidity of the wooden structure to prevent the flexing and bowing which cracks the epoxy paint.

Mark, I noticed that you used epoxy resin. That's what I was planning on. It's cheaper than the 2-part epoxy paint. You also mentioned that you only used 2 cups to do the bottom and sides. Do you think 1 gallon would be enough for me to do the inside and outside back of the tank?

Epoxy resin doesn't have nearly the fumes of the epoxy paint either. Plus it'd work better for the fiberglass taping in the corners. David used fiberglass with epoxy paint, which isn't designed for composite work.

I don't think it'd be necessary to double-up the plywood for my case. Lots of screws, liquid nails, and adequate top bracing should be fine.

Thanks again!

-Tom

[tomason]

I forgot a couple things:

The cheapest places I've found to get fiberglass related materials are these:

www.mrfiberglass.com
www.coastalmarineonline.com (horrible navigation, just search for what you're looking for, like "epoxy resin")
www.tapplastics.com

Also, David Grigor's site has this picture:

http://www.thefloodedbasement.com/Tank_status/Tank_installing_glass.jpg

That looks like a really good way of installing the glass. What are those stands?

[GARFVolunteer]

MarkS

Common sense has everything to do with it when you are designing a calcualtor for others to use. Your plans make sense but the way the calculator was before I put the limits on it, someone out there would have tried building one like it with 3/4 inch plywood. We decided to error on the low side with the linits. The wording could have been better and said something about "The calculator is limited to...."

Eventually the calculator would have evolved to handle larger tanks as time allowed me to work on it. However it is a mute point now.

Thanks,

Scott

[MarkS]

You are right and I apologize. I would delete what I wrote, but it's well past the 1 hour limit...

[JohnM99]

My friend and I built a plywood tank 10 feet long, and 24 by 24 - with a thin wood brace I think 1 3/4 " wide every 2 feet.

This was in about 1970, in his parents house. We moved on in life, but the tank stayed behind. In the 80s it was moved to a Chinese restaurant, owned by a friend of his - still going strong over 30 years later.

But don't skimp on the bracing - anything that will prevent movement will do - rods, acrlyic, anything - I thought I could get away with a 4 foot span on another tank. WRONG. I described the disaster in another thread. But a brace every 2 feet seems to work. And don't skimp on the glass quality!

That price for Starphire seems way too high. Maybe you can get it cheaper somewhere else.

[tomason]

Thanks, JohnM99. I was planning on putting a 3" rim of plywood all around the top (just like the face - 1 sheet routed out) and then 1 brace every 2 feet, so 3 braces total.

I'm going to use a sheet of tempered 1/2" glass, so that should be fine too. The price I was quoted for Starphire glass above was for TEMPERED 1/2", if that makes a difference. 1/2" though doesn't seem thick enough to be a big deal from pictures I've seen. I know it's been discussed before around here so I'll do some searches, but if any one has comments to make on that I wouldn't mind! ;)

I'd also be interested in reading your "disaster thread." :) There were a couple other scary ones I read, but this one takes the cake so far: http://www.dudeiknow.com/aquarium

That Devoe 233H Bar-Rust paint is looking mighty tempting.....Maybe I won't bother with the fiberglassing ???

Thanks, everyone!

-Tom

[swilbs83]

Someone on saltwaterfish.com has a 1700+ gallon shark tank he built with plywood(1 viewing window). The thing is huge and absolutely beautiful. Been running for about a year now. Do a search on SWF.com for user "novice150" and you will get his posts/website detailing the construction(alot of pics too).

[JohnM99]

Here is the link to my horrible memory
http://reefcentral.com/forums/showthread.php?s=&threadid=242232

After I put an angle iron brace on the tank, and coated it with fibreglass, the tank was fine. With a new pane of slightly thicker glass. My brother has it - still working.

We put fibreglass tape on all the seams and painted with some special fiberglass type paint (can't remember)

With the starphire, maybe the tempering is the reason for the high price ? I am getting my 90 flat back hex made from starphire (front and sides) and it is pretty reasonable.

Good luck. I had over 10 plywood tanks at one point - very affordable, and durable.

[tomason]

Yikes! So it was the glass that gave way?

swilbs83, jayo's post up at the top was for a 1700 gallon shark tank. I've seen that article at at least 3 sites, so maybe that's what you're referring to? It is awesome!

[SPC]

Originally posted by tomason
I'd also be interested in reading your "disaster thread." :) There were a couple other scary ones I read, but this one takes the cake so far: http://www.dudeiknow.com/aquarium

Yea that link definately shows how important the sealing coat is:eek2: .

I noticed that this guy said:

"Today I purchase 3 sheets of plywood. I know that my original plans called for AC grade plywood, but I decided to go with CD grade. Aside from a few "cosmetic" flaws, the plys seem to be better filled in the CD grade. Remember AC grade is more of an INDOOR wood, CD is more of an exterior wood. I HOPE this decision does not come back to haunt me later on."

I will hopefully be building a large plywood tank during the next year, I will be using birch or other cabinet grade plywood. No sense in skimping at this stage IMO.
Steve

[marm64]

I just recently bought 3/4 birch plywood from Menards and it now has 9 plys which would be good. I do not know if this is at all the stores I looked on the plywood to see where it was made and did not say anything but 18 mm so I think that it came from Canada. I would look for cabinet grade since it would not have any voids and should have more plys.

[Shoestring Reefer]

Originally posted by MarkS
You are right and I apologize. I would delete what I wrote, but it's well past the 1 hour limit...
Thanks for staying cool, Mark. It's nice to see some good examples on message boards.

[javatech]

This is my plywood tank
it'a a 140gal with two part epoxy paint and a 45 mil pond liner to keep the rocks off the paint
http://groups.msn.com/JimsCichlids/plywoodtankphotos.msnw

[Tommyc]

I used 3/4 birch plywood. solid as a rock. also used two part epoxy with a bead of silicone in the edges. dont have a leak, but I do have some salt creep along one seam......some things I read when building it recommended waterproof glue in between all the plywood joints....the way I figured it, water shouldn't make it beyond the epoxy and silicone so I passed on that....maybe I shouldn't have. may be just the excuse I need to build another bigger one.

[tomason]

javatech, that tank is really cool! It was one of the tanks I looked at before. Nice work!

Tommyc, that salt creep sounds really scary! Maybe you oughtta accellerate your the schedule for your "bigger one" so it's ready before that seam gives way. :)

So here's my current plan based on all the information I've found and received here:

- Use exterior AC grad 3/4" plywood for all the sides.

- The front and top will both be single sheets routed out to a 3" rim.

- For additional top bracing, I'll attach steel brackets to the plywood top on the front and back to thread the rod through. That way I don't have a rod and nut sticking out the front, interfering with finishing the outside of the tank. Those rods will be placed every 2 feet for a total of 3.

- To seal the plywood, I'm going to use a couple coats of epoxy resin to prep the surface, and then lay 2 layers of 6" fiberglass tape along all the inside seams. That will be followed by another 2 or so coats of resin with some black or blue pigment (I haven't decided on the color yet). The outside of the back and part of the bottom will also be sealed, because that's where all the bulkheads will be.

- The window will be 1/2" tempered plate glass attached with silicone, of course.

I feel pretty confident that that'll hold water long-term without problem.

Any last words????

I appreciate all the help!

-Tom

[wiliiam]

sounds good to me Tom. Let us know how it works

[marm64]

- To seal the plywood, I'm going to use a couple coats of epoxy resin to prep the surface, and then lay 2 layers of 6" fiberglass tape along all the inside seams.

I was looking into building a plywood tank and all the reading and talking to people most said that they would not put the fiberglass tape in the seams. They all seemed to think that it did not add that much strength and it was a PITA to get in so it was not sticking up all over and was not easy to seal over.

[tomason]

marm64,

That's interesting. I've heard that too, but I've also heard people say it adds lots of strength. Those who fiberglassed the whole thing said they wish they had just done the corners. Many people have had success without fiberglass, so maybe I won't bother!

Thanks!
Tom

[marm64]

If you fiberglass the whole thing that might be different but if you just do the corners I do not think that it would make any differance. This is like the people that think that they should use exterior grade plywood just be safe for a leak. If it leaks the exterior grade plywood is not going to make any differance. If done correctly I do not think that the fiberglass is just going to take more time than it is worth to do. But i guess if it makes you feel more safe I would do it for that reason alone.

[tomason]

That's a good point, marm64. I really don't know much about working with composites. Epoxy paint is sounding better and better!

That Devoe Bar-Rust 233H stuff they used in the thread referenced at the beginning can even cure at temps down to 20 degrees. As we head into winter, that's a really good thing! Epoxy resin and other epoxy paints require warmer temps which I can't give them very easily.

Does anyone who knows more about fiberglass want to put in a plug for it?

Thanks again!
-Tom

[Shoestring Reefer]

Has anyone built a plywood tank with multiple viewing ports on one side, like a 16' or 24' long tank?

[Mastino Mike]

Here is my 700g plywood tank with rubber pond liner and acrylic front. It going through a shakedown. No leaks. I should be finished in about a month.

[Mastino Mike]

Rubber pond liner.

[Mastino Mike]

First test fill.

[Tommyc]

I didn't use the fiberglass anywhere on mine and only one viewing area (front pane). But I do have one bit of additional advice......after my tank cycled I was fighting a significant hair algae problem. In the course of solving the prob I added a small urchin. Don't think he solved the hair algae problem, but it's all gone now. Point is....as the walls of my tank became covered with coralline, he chewed through the coralline, through the epoxy and into the wood. Not good. Just a word to the wise. Was able to fix the prob and the tank's still running great....but it was an annoying lesson.

tom

[Shoestring Reefer]

Did you fix while the tank was full of water? How?

[EnglishAl]

TommyC
Did you consider lining the tank with 1/4" (or 1/8") acrylic after doing all of the sealing etc? I am considering a plywood/glass tank and am thinking of doing this although I had not though of the problem you encountered. Makes me more inclinded to do it now.
Alan

[tomason]

Mastino - That's a cool tank! Was the pond liner all you used to seal the plywood? Did you just use silicone to seal the acrylic viewing pane?

TommyC - How did you fix that?

Are there any other creatures like urchins which can chew through the expoxy? I've heard of plecostamus doing it in freshwater tanks. Will falling rocks crack or chip it? I'm just wondering how likely this is...

Thanks!
-Tom

[blindhog1]

Here's a tank I built with three viewing windows it's 52" long 30" wide and 28" high.

[blindhog1]

sorry here's the pic.

[Mastino Mike]

All I used was a pond liner to seal the plywood. I dont want to ever worry about leaks. I have more pics of construction if you want. I sanded the area first, used weld-on 16 to glue it to the acrylic and then I siliconed over it. Thanks tomason, It is going to be a fowlr.

[tomason]

Hmmm, that's an interesting idea. I hadn't heard that one before. How much was the pond liner? It seems like it would be a pain to smooth out. Did you do anything to attach the liner to the wood?

[Mastino Mike]

If you buy a flexible rubber preshaped liner to fit your tank you wont have to worry about wrinkles. The water pressure also smooths it out. The liner is very tough and strong. My liner cost me 225 including shipping. Firestone edpm 45 ml thickness.

[Mastino Mike]

My pond liner is a 20 x 20 sheet and is very easy and simple to install.

[EnglishAl]

Mastino Mike
I am considering a plywood and glass tank and had thought of the idea of using pond liner but having installed on in my Koi pond I was not happy about all the wrinkles I would get trying to fit it into the corners. I know that you can use adhesive to glue pieces together so I guess you could cut the liner to fit and overlap and glue the seams. I was headed down the 1/4" acrylic liner route until I saw you post.
Where did you get it from? Also did the manufacturer custom make it for you because in your next post you mentioned a sheet of pond liner?
Alan

[Mastino Mike]

Whats up EnglishAl?
I bought my liner from justliners.com it is 45mil rubber edpm. Very flexible. Im not sure if they will make a box cut liner to your specs but there are rubber flexible box cut liners you can purchase if you are worried about wrinkles. If you are going to use bulkheads make sure you only cut through 1 layer of the liner when installing, so you will have a flush fit.

[EnglishAl]

Thanks Mastino Mike. Where can you get "box cut liners"?
Alan

[Mastino Mike]

I may be wrong about the edpm box cut liners? I used a flat sheet. They make them in butyl rubber, and Vinyl. Butyl is very flexible, strong and uv restistant also. I dont know how flexible the vinyl is but you could call and get a sample. To me the wrinkles arent that bad, because of water pressure, and Im just happy to have tank that big. If you are looking for no wrinkles then preshaped is the way to go.

http://www.pearlsofparadise.com/page2.htm

[Mastino Mike]

Started to clear up a bit but Im sucking a tiny bit of air on one of my pumps that I have to fix.

[tomason]

Mastino, You're right about the water pressure smoothing out wrinkles! That picture looks great! Because I wouldn't need any liner for the window side, like you, I would only need a 5.5'x15' sheet, which would be $34.65 before shipping at www.justliners.com. An acylic viewing panel is also cheaper than glass!

As for bulkheads, you said to "only cut through 1 layer of the liner when installing, so you will have a flush fit." What exactly do you mean by that?

Where did you hear to use Weldon-16 to attach the liner to the acrylic? I'm not sure how that would work, because all that would do is soften the acrylic, so it doesn't seem like a very good bond would form. Just curious!

So does your acrylic viewing pane butt up against the endpanels? The "standard" plans call for a viewing pane that ends up being about 1/4" from each side and resting on the bottom.

Thanks!
-Tom

[Mastino Mike]

I went out and picked up scrap acrylic pieces and ordered some pond liner samples of various types of pond liner materials. I Like the edpm best. I then tested several types of glues. The thinner weld-on numbers dont adhere as well as #16. Super Glue adheres very well also. All of this was after sanding the area of the acrylic before making attatchment. Weld on #40, I here might work best but I didnt try that one. I would silicone over the attatcment after it dries for two days. Then let that dry for another two. The water pressure holds the liner in place and helps form a water tight seal. Make sure you position the liner so the glued area has no tension wen filled. When folding the liner you create more layers of liner to cut through for bulkheads. Just be mindful of bulkhead holes and folds.(dont cut holes through folds). I have 3 1/2 inch frame going around the front(braced with 4 x4s), and it rests on the bottom.

[Mastino Mike]

If you are going to try the liner route, Purchase a liner that is also too big for your tank that way you have room for error.

[tomason]

Thanks for the info! The liner sounds like the safest way to go. I could also save money by not getting the smoothest plywood, because I won't have to paint it.

How did you attach the liner to the plywood?

[Mastino Mike]

I just tacked down the top of the liner around the rim of the tank with 2x4's but if you are using just plywood with no frame you might have to figure a way to tack it down. Maybe you could fold it over the rim of the tank and then tack it down with some type of decorative molding.

[tomason]

Ok, that's what I thought based on one of the pictures you posted. I'll have a top rim on mine, so I can do something like it.

Thanks!

[Sean : EbN]

On a side note...

A friend of mine built several plywood tanks, mostly 50-100 gallons each. He build and repaired boats for a living and he had many interesting ideas for the strong construction of the plywood tanks.

#1 - Ever think of using a 3/8 inch rabbeting bit on a router to make all the edges more complex. This is more surface area to glue to and seemed to make a stronger bond.

#2 - He also used some Epoxy Resin that was thickened and made a "D" shaped applicator and used that to fill the seams on the inside. It resembled a silicone bead and seemed to strengthen the design and also made a "seamless" appearance to the inside.

#3 - After all that he painted it with an FDA approved 2-part epoxy paint but I am unsure of exactly what brand name or type it was. I remember him saying they use it to coat potable water containers on ships.

I'm SERIOUSLY thinking about taking part in a wooden tank just for the hell of it. You guys really got me thinking....

Hope this helped...

Sean

[ChrisB]

I am also thinking of building a plywood tank. Can't decide on size. I have a basement that has a finished rec room with an adjoining area that is 16x30 that is unfinished. I am thinking of building a 300 to 500 gallon tank in the wall.
I had my mind made up about how I was going to do it, until I read this current thread about using pond liners. Hmm. I am using glass. If I thought I could get a good bond of the liner with the glass without weakening the liner I might just try it.
One question about the epoxypaint. I noticed someone saying they were going to add pigment to theirs, blue or black. Does adding pigment to a two-part epoxy paint not alter/weaken the paint? I would love to paint mine black inside if I decide against the liner idea. My project is still a month or so away from starting but I'll continue to lurk until then. Just trying to line up a those darn ducks. :) Thanks

[Mastino Mike]

The edpm pond liner works when sealed with just silicone against glass. I have a friend that has a 750 or 800 sealed with silicone against glass. Silicone would be all you would need. His tank is at least 8 years old but all he has now is a huge olive green moray in it.

[EnglishAl]

Everyone
In light of the potential for some critters to bore through corraline, liner and plywood is anyone concerned with using pond liner???
I hadn't thought of using rubber (was thinking of using 1/4" acrylic) until I started to read this thread then I saw the problem that TommyC had with the urchin.
Any thoughts on the subject?
Alan

[Tazzmacd]

EnglishAL, I was talking to a friend of mine who does acrylic construction and passed the idea about the 1/4" against the plywood to line the tank with and then a 1/2" piece for the front. His only concern was that you could have an issue with the 1/2" bonding to the 1/4" stuff properly. Oh the bond would be there but if you didn't have the plywood resting against the acrylic perfectly, then the seam could blow on you. Even the slightest space could cause enough pressure to make the seam blow.

That was his only worry. But I like the pond liner idea. Now the question is the seal using the acrylic front panel. Something to look into.

Cheers!!

Pat

[tomason]

Sean : EbN - Those are good suggestions. I'm no wood-worker, so I can't comment on #1. I was thinking about doing #2 (called filleting). It does greatly increase the strength (based on what I've read, 'cause I"m no composites expert either). #3 is a good way to put a layer of color on the outer layer of resin.

A couple of tried-n-true, save paints include:
1. Sweetwater epoxy paint, by Aquatic Ecosystems (www.aquaticeco.com)
2. Devoe Bar-Rust 233H epoxy paint. http://www.devoecoatings.com/index-working.html. You can use their "Service Locations" page to find a place near you that sells it. Here's the mini datasheet: http://www.devoecoatings.com/minidatasheets/233H.pdf. This is what I was planning on using before Mastino Mike brought up the pond liner thing. A pond liner isn't going to crack if it flexes a little bit. Plus it's cheaper.

ChrisB - As for you question about epoxy paint: You don't need to add any pigments to the paint. You can just get whatever color you want that they make. I mentioned adding pigment to epoxy resin, because the resin is basically clear. It does affect the properties of the resin a little bit though, so pigment should only be added to the last 1-2 coats.

-Tom

[ChrisB]

Called about the 233H epoxy paint. $64 gallon. No idea how much it might take. Dimensions likely to be 8x4x2. Anyone have an idea?

Tom -Where would you go to get the resin for "filleting"? Would you just ask for epoxy resin? The resin in the seams sounds better to me than using fiberglass.
The resin would go on before the paint, right?

[nematode]

This is another approach to building tank you can consider.

wood frames with plywood sides,bottom, glass front/sides. Sealed with silicone and waterproof 0.06 inch thick white plastic paneling.

description of the general methodology- though sides of the all but the 100 are done with frames instead of stacking 2 x 4
http://homepage.mac.com/nematode/IMAGES/100gTDIY.html

a 29 gallon built from oak 30x17x 21 h
http://homepage.mac.com/nematode/IMAGES/29.jpg

still running strong.

a 100 g from pine 72 x 27 x 17 h
http://homepage.mac.com/nematode/IMAGES/100tanksetup.jpg
also seen behind 250 picture below, and below 260. developed very small leak after two years. I think it was from twisiting when I lowered it to below the 260 with sand in in and it twisted and creaked a lot during the move.

a 250 from pine 50 x 48 x 30 h

http://homepage.mac.com/nematode/IMAGES/250sm.jpg

http://homepage.mac.com/nematode/IMAGES/250tanksm.jpg
taken down after six month cause it was an poor shape- too deep,

a 260 from pine 96 x 36 x 21 h
(5/16 inch glass)

http://homepage.mac.com/nematode/IMAGES/500sysbasesm.jpg
Running great - this is an old picture before I removed the 100 from below in august

personally, I think this is much more likely to last long term than a liner system if you have urchins etc.

I'm certainly not sure it is as sturdy as a well-done epoxy paint or fiberglass sealing job, but it sure is a lot easier and a lot less smelly/messy.

[tomason]

ChrisB - The liner is definitely cheaper than the expoxy paint and resin! The cheapest places I found epoxy resin online are at www.tapplastics.com and www.mrfiberglass.com. To make the resin thick for filleting, you get a filler. TAP Plastics has Cabosil and the other place has something like it. Add filler to make the resin thick enough. Then you can put it in the seam and smooth it out with a stir stick or something. Be sure to watch your pot life, so get something that cures slowly or be fast!

Nematode - That's a cool idea too. That's a really cheap way of sealing the inside. The seams would still concern me though. That's the weakest part anyway. Perhaps a combination of methods would be best.

For example, you could use the plastic sheet to seal the sides. Then get just enough epoxy resin and some filler to put a fillet along all the inside seams. That way you don't have to buy $100+ worth of resin to seal the flat sides, but you get the strength of the epoxy in the weakest parts. That'd probably be cheaper than a pond liner too, and perhaps more resistant to urchins.

Maybe an even better combination would be to use the plastic sheet for the sides and then a strip of pond liner material along the seams. That would have the flexibility of the liner at the seams where it would matter.

I don't know....Any other thoughts?

-Tom

[Mastino Mike]

What other critters out there could chew or burrow through a liner or epoxy besides urchins?

[ChrisB]

Wonder how UV resistant the plastic sheets are. I know some plastic breaks down and becomes very brittle after long term exposure to sunlight.
If it is highly UV resistant, I will probably lean toward using the resin AND pondliner on the seams, then use the plastic for the sides.

[Mastino Mike]

There are some pond liners that are not that flexible at all and uv resistant and are more like plastic that you could layer the sides of a tank with.

[Mastino Mike]

Here is another box cut liner site. I believe butyl is tougher but not as flexible as edpm rubber. Dont know the cost because it is over seas. http://www.butylproducts.co.uk/Products-services/Ponds-Lakes/DesignGuide/

[Mastino Mike]

http://www.butylproducts.co.uk/Products-Services/Ponds-Lakes/DesignGuide/

lets try that again.

[jfinch]

Tomason, are you the Tomason from AF? If so have you talked to KeoDog about his 300 gallon plywood tank? If none of this makes sense... sorry for the intrusion.

[EnglishAl]

tazmacd
I think you may be right about the need for a very good fit of the inner acrylic box to the outer plywood box. My concern had been the problem of sealing the glass front to the acrylic sides. I know that silicone will not stick to acrylic.
I have sent an enquiry to the company in England that Mastino Mike posted. I figured that I would cut an opening in the front panel of the box liner to match the front frame and then seal the glass against the strip of liner that remains. With this method the pressure of the water would "force" the liner into a sort of gasket between the glass and the plywood (or in my case stainless steel) front frame (plus silicone of course).
I am still worried about boring critters and from what I have read in this post no one seems too concerned.
Alan

[tomason]

jfinch - yeah I am! I didn't know he had one.....I'll PM him today and maybe talk to him at the meeting tonight.

EnglishAl - I was thinking about doing the same thing with a fitted liner. I asked Pearls of Paradise about their fitted liners and what I should use to attach the panel with, and they mailed out a sample to me yesterday for me to try some things with. I'll let you know how it works. I've got weldon 16, silicone, acrylic, and glass, so I can try a couple combinations at least.

-Tom

[Mastino Mike]

Here some food for thought. The attatchment of the liner against the acrylic or glass does not have any tension on it so it doesnt have to be super super strong. You are just trying to create a water tight seal and the liner will be held in place by water pressure.(you create a lip or attatchment on the inside of the glass or acrylic behind the front frame of the tank). Im not worried about any critters burrowing through the liner because Im just doing fish but for you reefers maybe it is a major concern depending on livestock choices?

[EnglishAl]

tomason
Thanks - keep us up to date. Please see the attached sketch for an idea that I might try.
Alan

[EnglishAl]

Well let's try that again

[EnglishAl]

Footnote
I'm still not too happy with a liner that some critters can bore through. I've not seen any comments in this thread. I will start separate thread - maybe that will elicit replies from others with experience.
Alan

[Mastino Mike]

EnglishAl,
That looks good and might work great if you use enough silicone but I have my acrylic up against the plywood and liner on the inside of the acrylic. That way you have the liner and the silcione forming a seal. If the glass or acrylic bows then you might have a problem with you seal

[EnglishAl]

Mastini Mike
I'm not sure what you're saying - I thought my drawing showed the glass sealed to the liner with silicone.
Alan

[ChrisB]

Your drawing has the liner on the outside of the glass, sealed to the glass and the outside frame. I believe Mastino is talking about having the liner be the innermost layer sealed to the glass only. That is the way I was thinking of doing it myself anyway.

I am also concerned about creatures chewing thru the liner. My head is spinning over this. At this rate, I will have a dozen layers of crap before Im done. :)

[Mastino Mike]

No one has responded to Englishal's post yet in general reef discussion concerning boring or chewing critters? It will be good to know what to stay away from.

[nematode]

I've never seen significant damage on rubber suction cups in any aquaria I've had. So I would guess that boring problems would be limited to larger animals with teeth- urchins, perhaps some types of turbo snails.

IME Both of these will do damage to plexiglas if it is allowed to be covered with coralline algae. When these animals remove the coraline, they dig iinto the plexiglas making scratches.

I personally would be more concerned about puncturing/damaging the lining with a rock-slide, or the like.

Bottom line is that by taking the cheaper DIY pond lining you are likely substantially increasing the possibility of a leak from puncture or boring.

How long do you want this tank to last?

When I built my homemade tank I accepted the fact that they might not last 20 years or even 5 years. If they last only two years, then at that point I can decide if I want to shell out $1000 for a professionally built tank (that might still eventually leak).

If you are absolutely sure you want a tank that will hold up for 10 years, I would argue that the additional cost of purchasing a professionally built aquarium will be minimal compared to the money you will put into the tank over that period in livestock, salt, power, lights, and the effort you'll put in to keep it up. So, I'd argue its not worth doing it on the cheap if your darn certain that the tank your planning is a relatively permenant fixture in your life.

[tomason]

>> So, I'd argue its not worth doing it on the cheap if your darn certain that the tank your planning is a relatively permenant fixture in your life. <<

That is a really good point! It'd sure be a pain to have to tear down the tank in a couple years...I can't afford the LR for the tank now anyway, so I don't have to decide now. We'll see!

-Tom

[Mastino Mike]

Good point. It is highly unlikely that the liner will puncture due to a rock slide. IMO the liner is very strong and durable for long term use and even more so with padding under it. I would say order some samples and check different types of liners out. For a Fish only or Fowlr it is perfect. You only have one seal worry about and that is the liner against the glass or acrylic. You can get them in 65 mil thickness. My 700 gallon tank, just the tank. Wood, liner, acrylic, glue, silicone cost me under 900 dollars. Where can you find a price like that?

[javatech]

When i did my 140 plywood and glass tank i used a two-part epoxy paint . the kind they paint water tanks with and a 45mil pond liner to keep the rocks and what not from hitting the paint . it's been up for a year and a half so far so good

[EnglishAl]

ChrisB and Mastino Mike
I intentionally did it that way so that the liner would act as a sort of gasket between the glass and the frame (with added silicone). I could put the glass next to the frame (sealed with silicone) and then silicone the liner to the glass but then you have to rely on the water pressure keeping the thin strip of liner against the glass. The way I propose, the pressure of the water against the whole surface of the glass transfers to the liner "gasket". As this is only a narrow strip, the pressure is quite high thus ensuring a good seal.
The whole point is moot though if the boring critter issue is not resolved to my satisfaction.
Alan

[EnglishAl]

mastino mike
I would not worry about puncturing either. I have a Koi pond that's been up and running for almost 8 years with no problems. Even when the neighbors little rug rats took all of my rock from the waterfall and tossed them in the pond :mad: :mad2:
I am more concerned about borers. Perhaps an inner lining of plastic or Acrylic panels glued to the liner would be the way to go. You wouldn't have to worry about sealing it as it's only there to protect the rubber. Now there's a thought.......... :idea: :idea:
Alan

[Soren]

Greetings... I was the guy with the "takes the cake" horror story (Soren's 300 Gallon Plywood / Acrylic Aquarium (http://www.dudeiknow.com/aquarium/) )

I know I'm WAY behind on updating my website, but everything has worked out great on the aquarium. I've had it up and running since early August with a few minor problem, but nothing major at all (with the exception of one of my Rubbermaid sumps cracking and leaking!).

The initial leaks I had while building the aquarium were due to the following reasons:
1) my bulkheads either weren't tight enough or need more silicon on them

2) I didn't coat the tank enough times with the epoxie paint. Plain and simple... I used a full gallon on it at first and it wasn't enough... after using an additional 1/2 gallon I didn't have any problems or leaks from the tank itself.

I hope to finish up my website soon with updates and current pics.

I used acrylic for the front sheet.... and I have been very pleased with that decision. It is LIGHTER and easier to see though then glass. So far I've found that using a BLUE pan scrubbie pad does not scratch the acrylic (never use the GREEN one... is rougher and tougher and I've even seen it scratch GLASS!).

I hope that I can instill a sense of confidence in the epoxie paint... even the lower grade plywood I used has been fine (which was of some concern when I was initially building the thing). IF I could do it again, I would probably spend MORE on the plywood... maybe get a nice OAK or BIRCH, but frankly out here in Arizona wood of that quality in 3/4" thickness run quite a bit.

Soren

[tomason]

Hey, Soren

That's good to hear! There are several plywood tank accounts which document building the tank but don't have updates indicating whether it's still working or not. I'm glad yours is working!

Aquatic Ecosystems recommends epoxy paint to seal plywood tanks too. They have instructions on their website. It may be that this thread is more about paranoia and finding peace of mind rather than just coming up with a method of building a plywood tank that'll work. :)

As for the critters that chew through the tank lining....It'd be nice to know how much of a problem this really is. Are we getting nervous about being struck by lightning? While an urchin isn't going compromise the water-holding ability of an acrylic tank, if it can chew through epoxy, then it can definitely scratch the acrylic. It seems like this would have been encountered before....

Just wondering!
-Tom

[EnglishAl]

tomason
I agree with your conclusion - I too am not really concerned as to HOW to build the tank (I am a woodworker so I know all the stuff about plywood, glue, joints, etc.) it's more about having peace of mind with my final decision on waterproofing.
I'm still paranoid about the boring question (no pun intended). :D
Alan

[Mastino Mike]

EnglishAl,

Do you want to keep urchins? What are you planning on keeping? I guess that is the most important question. What type of "critters" come on live rock that you really need to worry about. How can you avoid any potential chewing or digging inverts?

[Mastino Mike]

I would also agree that waterproofing is the most important thing. Basic tank construction is fairly simple.

[SPC]

Originally posted by tomason
Aquatic Ecosystems recommends epoxy paint to seal plywood tanks too. They have instructions on their website.

Hi Tom,

Do you have a direct link to these instructions? I looked all over the site but could not locate this.
Thanks,
Steve

[EnglishAl]

Mastino Mike
Thats' the problem - I don't know what I'll be keeping. Also you never know what hitchhikers there will be on live rock. I guess what I want is the peace of mind I would get with a glass tank.
Alan

[Mastino Mike]

EnglishAl,

Well what size tank do you want? I think that plywood tanks are not worth it if their under 200g. Just my opinion. They only save money if they are extremely large.

[ldrhawke]

I would like to add a warning to those that have built and are building plywood tanks based on my unhappy experience in building a 1000 gallon tank a number of years back.

I double up 3/4"marine plywood. Fiber glassed the insides and coated the tank with several coats of 2 part epoxy paint. I used 5/8 " glass and silicone sealed it. Everything went fine.......the system was into about five months of cycling, and I had a few fish and coral in the tank.

I went I a skiing trip with my family and got an emergency call one evening from someone we had watching the house. This person knew little about fish and I'll always remember his comments......" I think your fish are sick"

I asked why he thought that and he replied, " They are all sleeping on the bottom of the tank"......OH Sh#t! All the water had leaked out of the tank.

What I found when I got home was the water was leaking around the glass. I couldn't imagine why because I used plenty of silicone between the glass and the plywood tank. I tried to re-silicone and seal leak both from the inside and out, but it would only come back after a week or two.

I finally decide I had to completely remove the glass and reset it. When removing the glass I discovered the problem....!

The silicone and epoxy are not compatible. While silicone is sit wet it reacted with the epoxy paint and virtually pealed it off of the fiberglass. The silicone stayed wet and didn't cure deep in the heavy bead I had made and reacted with the epoxy paint. The water was leaking between the paint and the fiberglass...no amount of silicone sealant would have solve the problem....In fact the more I used the worse the problem was because it slowed the curing process and gave it more time to react with the epoxy.

I hate to be a domes day courier, but it a problem anyone building a tank this way should be aware of.

From the great tank articles posted it sounds like a few have already leaking problems.........my bet it is caused by what I described.

[EnglishAl]

ldrhawke
Thanks for your input - sorry about the problem you had. I think the idea of using a rubber liner that would form a barrier between the plywood (sealed or not sealed) and the glass would solve that problem.

Mastino Mike
I am going to build a 120 gallon tank. I have a price for an all-glass tank from Bow Valley up in Canada for around $800 delivered (with Starfire front). If I use a preformed (box cut) liner, stainless steel angle frame and Starfire glass front these will be the only real expenses (I have the plywood in my shop). I am guessing that the glass, the frame, and liner will be about $450 so it should be worth it but we'll see when I get prices. Did you use Starfire glass for your front? If so how big and how much?
The other issue with a large all-glass tank is weight. A 120 weighs around #300 empty I think. Plywood is much lighter and stronger - the waterproofing is the only problem.
Alan

[Mastino Mike]

Ive never used epoxy, so I dont know much about it. Ive seen a pond liner used with glass and its had no leaking problems over 8 years at least. Ill post a pic of this tank as soon as I get a chance.

[Mastino Mike]

EnglishAl,
It feels great to build and do things yourself but for a 120g tank I would just buy a tank, thats if your concerned with with chewing or boring inverts. Although you could probably build something that looks alot better because you are into woodworking?

[tomason]

SPC - I can't find it either now! :) It wasn't much different, if at all, from other methods, so I didn't pay much attention to it. Just build the frame out of wood and seal it with epoxy paint. The instructions were part of a larger pdf. Building a tank out of plywood was just one part of it. I only mentioned it because you could get the paint and instructions in one place. Oh well!

ldrhawke - Man, that would really suck! What kind of paint and silicone did you use?

[blindhog1]

ldrhawke
I belive that useing epoxy over the fiberglass was your problem. The two materials are not compatible with each other. Fiberglass resin is a polyester resin and not an epoxy, and epoxy will not adhere to the polyester resin like it should. Wooden boat builders use epoxy resin to glue and seal the wood and paint it with an epoxy paint. Silicone will adhere to the epoxy pretty good if you sand the epoxy with 220 grit sandpaper first.

THE HOG

[salty joe]

Mastino Mike,

EPDM liner sounds good to me. Can you go into a little detail concerning viewing panel attachment? If I got it right, you use Weld-on 40 or something like it to glue acrylic inside opening of plywood box. Then you use silicone between acrylic & EPDM. If this is it, how do you hold EPDM flat while silicone cures? Doesn't water pressure force the EPDM against the corners of the acrylic panel, causing tear points?

Joe

[Mastino Mike]

Position the liner loosely in the corners so when filled the rubber doesnt stretch. The goal is to have no tension on the attachment. I just used a thin bead of silicone to hold the acrylic in place in the seams before installing the liner(the corners or tear points of the glass or acrylic that you mentioned) The liner is tough and it would take more than that to tear or cut the liner. The acrylic is not that sharp on the edges and I doubt it would tear the liner at all but I used silicone on it any how. I used weld-on first to glue the liner smoothly after sanding. You cant have any wrinkles in the attachment. Then I used a thick layer of silicone over the attachment. I then used weld on again in the seams of the silicone and the liner and the silicone and the acrylic dont know if that helped but I did it anyhow.

[Mastino Mike]

Salty joe,
Just fill any gaps or sharp points with silicone or foam. I have at least 3.5 inch frame on top and 4 inches on the sides of viewing frame. You also want the glass or acrylic to sit flush as possible my acrylic sits very tight in the front viewing panel without much gap between the sides.

[Mastino Mike]

Last,
Glass is very easy to install. Silicone would be all you would need. I would follow the same procedure except use just silicone. The goal is to form a water tight seal thats it. The attachment shouldnt have any tension at all when filled if it does then it was installed wrong and you may have some leaking problems or maybe not?

[salty joe]

Mastino Mike, Thanks for reply. Please excuse me if I seem extra dense, but I wanna be sure I've got this seal understood before buying materials.

Extra heavy duty plywood box, say 80"x40" front panel dimension, with a 72"x32" cutout.

Acrylic or glass viewing panel, 76"x36" centered on cutout and inside box, glued into place.

Inside front panel built up with plywood to be flush with viewing panel, so that viewing panel sets in a "pocket".

Cut a 72"x32" hole in the EPDM and silicone EPDM to inside of viewing panel.

Is this pretty much what you did?

Thanks,
Joe

[Mastino Mike]

Yes thats it! The pond liner being the inner most layer. Here is another tip about making the attachment. Glue liner in straight lines. Work your way down top right corner to bottom right corner and then right to left and so on. This way you will avoid wrinkles in the attachment.

[Mastino Mike]

Glue liner in small sections at a time.

[Mastino Mike]

I used a 4x4 frame so I would have something to tack down the liner to and add extra strength to the tank. My tank has no bow with no cross braces. Im going to add one because it might bow over time.

[SPC]

Originally posted by Mastino Mike
I used a 4x4 frame so I would have something to tack down the liner to and add extra strength to the tank. My tank has no bow with no cross braces. Im going to add one because it might bow over time.

Looks like those 4x's are pressure treated Mike, did you seal them in some way?

[Mastino Mike]

The liner overlaps them. I did not seal them, do you think I need to? They are not in any contact with water?
SPC

[Mastino Mike]

I did some research on pressure treated wood. As long as you dont have any direct contact with water or secondary contact from hands to water. It is fine. Outdoor ponds use pressure treated wood all the time. Thanx SPC it didnt even cross my mind during construction.

[SPC]

I wouldn't worry about it either in your situation, Mike. I know that some is used on outdoor ponds, but of course these are alot less sensative animals and to be honest, we really don't know for sure if it might be affecting some of the aquatic life in them.

The way I look at it, the EPA will no longer allow stores that sell lumber to cut pressure treated wood due to health concerns. This being the case, I don't think I'd want this wood to come in contact with my reef in any way.
Steve

[Shoestring Reefer]

Sweet! I'll keep that in mind when I need some more luxury neckties!