Plexi lined plywood tank? [Archive] - Reef Central Online Community

areze

02/12/2006, 07:34 PM

Im considering epoxying the tank and laying the sheet of thin(1/8 or 3/16") plexi into the epoxy. so the wood is sealed, and the acrylic is both supported and locked in. then do the next side and place the acrylic on that side, and all around.

then seal the edges, but Id definitly use weldon of some sort depending how the gaps came out.

only thing is I still want to make the viewing panel out of glass on mine.

ejmeier

02/12/2006, 07:46 PM

<a href=showthread.php?s=&postid=6725837#post6725837 target=_blank>Originally posted</a> by willjeff
Hello everyone, would this idea work. I was thinking instead of sealing a plywood tank with epoxy could you place pieces of plexigalss and then silicone the edges.
That is so weird, I was sort of daydreaming today and thought about doing that EXACT same thing. I mean EXACT. :p

The only problem I could see would be if the silicone doesn't stick very well to the acrylic. Maybe w/ expansion and contraction over time it might work loose???

I have a nearly 1 gallon of spare epoxy paint, but it would be so cheap to build one w/ acrylic lining. You wouldn't even need to have anything that thick, or even cast acrylic, as long as the plywood is reinforcing the load. (Of course the front would need to be as thick as regular tanks though.)

Let me know if I have said anything stupid. :)

areze

02/12/2006, 07:58 PM

weldon 16 would work just like silicone and solve all the problem with that.

I dont think Id go so far as to use extruded though. might be ok, but assuming a large tank, the money would be insignificant, specially compared to what your saving in epoxy thickness or a full fledged acrylic tank.

willjeff

02/12/2006, 09:07 PM

OK so it would work with epoxy paint. How much does epoxy paint usually cost?

ste6168

02/12/2006, 09:33 PM

thats a real good idea, i bet you could use 1/4 inch and it would work fine and then use something thicker as the viewing pane.

ejmeier

02/12/2006, 09:39 PM

<a href=showthread.php?s=&postid=6727148#post6727148 target=_blank>Originally posted</a> by willjeff
OK so it would work with epoxy paint. How much does epoxy paint usually cost?
About $60/gallon if you want the stuff approved for drinking water.

willjeff

02/12/2006, 09:42 PM

Yeah it should be really cheap to do. Would it be possible to install bulkheads on something like this? I don't see why not but I am tired and probably not thinking clearly, long weekend.

ejmeier

02/12/2006, 10:34 PM

Yes, but the flange/gasket has to be on the inside of the tank. (With solid glass or acrylic its either/or since you can seal it from the outer side of the material.)

willjeff

02/12/2006, 10:40 PM

Cool now I just have to figure out how big to go and where the heck I can put a large tank. The wife I'm sure will be thrilled when I tell her I am making a plywood tank.

areze

02/12/2006, 10:56 PM

yeah its a find design. if ANYTHING could fail; you could secure it very easily with an acrylic rectangle bar in the corners, that would give you the corner strength if you wanted to use REALLY thin wall material(1/8th"). I only say the rectangle reinforcment in the corners because perhaps the 1/8" doesnt have enough material to actual join. but a simple addition to the corner will give it more to grab.

get the cheapness of a plywood box, and the flexibility and absolute water proof-ness of acrylic. Im all about over engineering.

IMO you dont need such expensive epoxy either. the epoxy most use needs to be water proof and reef safe. in this case you need neither. the epoxy's only purpose is to ensure the acrylic is fully supported to the wood box. you can use the cheapest thing smoking infact; its strength doesnt matter, its adhesion doesnt matter, nothing about it matters. as long as it dries and has some minimal amount of strength its good. even if it cracks, its no problem.

RandyStacyE

02/14/2006, 12:19 PM

I would check out www.sanitred.com

This is a life time warranted coating system that is tough as a truck tire! Epoxy is way too unreliable since they become harder more brittle with age. Fiberglass fails and is too expensive in comparison and nowhere near the performance.

areze

02/14/2006, 12:26 PM

the acrylic lining solves those problems though.

you can even join sheets of acrylic together as well if you want a HUGE tank.

NorthFace

02/14/2006, 03:05 PM

HEY! HEY! You stole my idea!!! :D

Check out Sean's Plywood Tank thread...I just asked him about this, on the 8th.

http://www.reefcentral.com/forums/showthread.php?s=&threadid=716410

I think it's a great idea and I'm gonna try for a 96 x 48 x 24 tank, lined with 1/4" acrylic, with a viewing window of 3/4" acrylic.

willjeff

02/14/2006, 03:36 PM

That sanitred stuff sounds pretty impresseive. RandyStacyE have you used this product.
Like areze said the lining is the water proofing, plywood is for strength and reinforcement, and then use whatever sealant wround the edges or coat the whole inside to prevent leaks. I would like to find out if anyone has tried this. Or if I am overlooking something here.
I have had some ideas of the tank just being a lookdown style, maybe with some type of earth toned tiles along the edges. If this idea makes any sense. The top would be about 4 ft. high, that way you can lean over it and look down like a tide pool.
Any Thoughts?

areze

02/14/2006, 03:43 PM

it would require additional lighting, since if your looking down at it, youd need much more light on it with it being higher off the surface.

Its not my bag, but thats a personal preference. I think lighting is the main issue to consider.

epicentyr

02/14/2006, 04:04 PM

willjeff

If you are a premium member or have superpowers you can search for "huskerreef" he built a 1000 gal sump that is just schweeet!

As for this thread the ideas are good but the amount of contact area for a solvent weld on .125 in acrylic is tiny. maybe try to find a 1/4 round or acrylic cove molding to seam the corners for a larger contact patch.

willjeff

02/14/2006, 04:06 PM

I see where you are coming from, with the need for more lighting on something like that.
For a traditional style tank would it be possible to still use plexi on the top and edges to prevent rotting?

willjeff

02/14/2006, 04:20 PM

Epicentyr the molding idea is very good. I really should become a premium member. Is the "huskerreef" a lookdown pool?

willjeff

02/14/2006, 04:40 PM

Actually northface I have been checking out that thread also. He did some really nice work constructing everything. I don't feel that I can match his craftsmanship though.

areze

02/14/2006, 04:44 PM

I think some epoxy would still be nescessary; for the bracing on top, and I think Id pretty much give 1 coat to the outside of the tank just for peice of mind to be sure the humidity doesnt hurt it long term. and so I can wipe the surface down from salt and stuff.

but the plexi should still cut down on many gallons of 100$ a gallon epoxy.

and most of all, its more durable.

willjeff

02/14/2006, 05:21 PM

The idea epicentyr had with the cove molding would also work if you used it in the oppostie way for an overflow. You are right areze epoxy should be used over the whole thing, just to be safe.

nonot8946

02/14/2006, 09:15 PM

it would probably work if:
1) the wood didn't warp
2) it was cheaper than fiberglass

I bet cheap glass could be had, it's not like you need to have high quality except for the front, plus it's easier to put together.

lfjewett

02/14/2006, 09:49 PM

This thread really interests me. I've been looking at plans for a large ( near 300G ) tank in my new home. I want three side viewable and the ability to use acrylic bonds and plywood strength seems a little "too good to be true".

So to the experts out there using slim 3/16 ths material for the bottom it be possible to seem a 3/4" front viewing panel in place?

Would adding a 1/2 inch or 3/4 inch acrylic square stock to all the seems give adequate surface area to create good seals?

If the square stock were to be used at all the seams how would one go about sealing them? I've seen threads on bonding 2 surfaces together but 3 surface at once where gravity can't help on one of the seams? Weld-on #40 or Weld-on #4?

slevesque

02/14/2006, 11:00 PM

Hi, funny I had the same idea last week.

At my workplace we are providing storage for different company and one of them made a big cleanup in their stuff, trowing out acrylic. I ran to recuperate a 5'x5', 1/4 inch piece. I also got 3 pieces 5'x1' and few 2x2 pieces. So many possibilities. :)

I was considering using only silicone to seal the edges. After all, the plywood is doing all the streight task. Since i dont have experience with silicone + acrylic I'll read a bit more around.

The idea of using an acrylic square stock is very interesting .

One last thing. There is another solution for a 'topview' only tank: using an EPDM pond lining sheet, if you don't mind the black color of it.

areze

02/15/2006, 10:10 AM

silicone doesnt really bond, so it is possible that it could shift or just kind of come lose and leak in the corners.

all things considered weldon16 is maybe 10-15$ so theres really no good reason not to use it.

slevesque

02/15/2006, 10:33 AM

the only Acrylic glue I can find localy is the weldon 2705 or the one they have at Home Depot, called oat, or something like this.

I agree, it would be better to glue and then add silicone for leaks.

Bill Wann

02/15/2006, 12:13 PM

Ive done this befor , acrylic dosnt work well , the joints flex too much when it filled with water and crack . 16 wont hold . Use pvc sheet , its cheaper and can be welded or siliconed in . Ive made afew sumps with plywood and welded pvc sheet , it works great .

Bill

slevesque

02/15/2006, 12:13 PM

Oatey pvc cement, this is the brand I can find at HD.

areze

02/15/2006, 01:30 PM

thats totally different, HD doesnt sell the acrylic weldon; gotta go online for it. or whoevers supplying your acrylic might have something.

bill wann- thats why Im thinking it needs to be epoxied into place so the walls are fully supported and hold no weight. there is no other way to really make the acrylic be fully supported at all point except to bond it with something liquid.

slevesque

02/15/2006, 01:55 PM

PVC sheet, never heard before. Is it sold at HD or alike?

TANGBOY5000

02/15/2006, 02:08 PM

Since we're on the subject I think I may have found a solution to something that has been bothering me. The plywood tanks are all awesome, but the amount of work involved is tremendous. I've also seen that alot of the time even with careful planning and work there is a leak. I got my usual catalog from US plastics yesterday. They have polyethylene tanks for very reasonable cost. I think the 500 gallon was about $1200. That tank is 6'L x 3'W x 4'H. They recommend reinforcing it with plywood and 2x4s if you're going to fill it up with liquid. So that tank is waterproof, food safe, and corrosion proof. Since it's made of plastic it is easily drillable for and drains you want to put in. They also say they can make them to any dimensions you need. Now for my question, does anyone know what will bond glass to polyethylene?

areze

02/15/2006, 03:01 PM

nothing... but the water pressure should maintain a seal with some silicone. if you applied pressure the other way though... it wouldnt be much of a bond.

I dont know if those tanks would hold their strength if you cut a side out though.

willjeff

02/15/2006, 03:02 PM

I am interested in the pvc sheet, the flexing and cracking was the thing that worried me. So areze your idea is to epoxy each piece of acrylic to its designated wall, then epoxy in a corner piece of acrylic to connect the walls, right?
Tangboy I am looking to get away from the $1200 price tag, other wise it would be a great option.

wildcats

02/15/2006, 04:44 PM

Would the acrylic have to be thicker than 1/4" if you limit the opening to say 12-16" and then its braced all around with wood to prevent flexing? Limits viewing but cheaper

areze

02/15/2006, 05:28 PM

that is my idea, lay in the epoxy then drop the sheet in. probably do bottom first, then front and back, and finally the sides. each time rotating the tank so the side your working on is on the ground; then the epoxy can just set there, and lay the acrylic sheet into place. should be fully supported then. all the weight transfered straight through to the wood.

could be difficult to do on a MUCH larger tank. my future tank will be 12x4x4' which IMO is still workable and able to be stood on its ends as well as moved with enough helpers.

as for the corners, the sheets of acrylic should be all jointed nicely, if the cuts are done accuratly weldon 4 shouldnt be out of the question, with some weldon 16 for additional corner strength. but yeah, a corner peice of acrylic for the seams could be a very viable option for additional strength, probably a better choice if you were to try thinner acrylic walls.

if you wanted an acrylic viewing panel you could make the front panel a full size sheet of nescessary thickness and bond it right into the tank and be 100% water tight, wouldnt have to worry about siliconing it in.

I want a glass viewing panel for scratch resistance though. willing to sacrifice that bit of sturdiness for it.

areze

02/15/2006, 05:29 PM

wild cats, youd probably be ok, it would depend where the 12-16" viewing window was though, Id say as long as the bottom of it wasnt anymore than maybe 20-24" deep you could get away with it.

willjeff

02/15/2006, 06:52 PM

Is there a specific epoxy paint that one would use, there are alot of them?

cb350z

02/15/2006, 06:58 PM

i like the idea of a cheap homemade tank. instead of plywood i was thinking about using the plastic that is used for boards in ice rinks. this white plastic comes in sheets that are anywhere from 4'x8' to 6'x14.' it also varies in thickness from 1/4inch up to 3/4 inch. it may be a bit more expensive than plywood, but u eliminate the 20 coats of epoxy paint.

areze

02/15/2006, 07:37 PM

its probably quite expensive. probably not too much less than acrylic.

wasnt a specific epoxy I have in mind, Im atleast a year or 2 off from doing it because of the multitude of other expensive equipment a tank in the 1200g range would require. when I get closer Ill investigate good epoxies, and probably go with a smoked 1/4" acrylic.

NorthFace

02/15/2006, 08:12 PM

My idea was to build the shell from plywood and then line with 1/4" acrylic. I'd probably sand the "outside" of the acrylic, so that it could be painted black...then, it wouldnt matter if you painted the inside of the plywood shell of not. Then, using Weldon, attach the corners of the sheets of acrylic together.

1/4" for the bottom and 3 sides and then a thicker sheet of acrylic (probably 3/4") for the viewing window.

areze

02/15/2006, 09:10 PM

it would be pretty difficult if not impossible to TRUELY get all the corners and such completely in contact with the plywood to truely take any and all weight off the undersized acrylic joint. it would be very important that the plywood be supporting the weight, otherwise it could be disaster. not to say its impossible to do, just extremely difficult.

RandyStacyE

02/21/2006, 11:20 AM

<a href=showthread.php?s=&postid=6740983#post6740983 target=_blank>Originally posted</a> by willjeff
That sanitred stuff sounds pretty impresseive. RandyStacyE have you used this product.
Like areze said the lining is the water proofing, plywood is for strength and reinforcement, and then use whatever sealant wround the edges or coat the whole inside to prevent leaks. I would like to find out if anyone has tried this. Or if I am overlooking something here.
I have had some ideas of the tank just being a lookdown style, maybe with some type of earth toned tiles along the edges. If this idea makes any sense. The top would be about 4 ft. high, that way you can lean over it and look down like a tide pool.
Any Thoughts?

Yes I have used it a few times and it works flawlessly every time. There is no doubt about it. No need for silicone, acrylic, epoxy, fiberglass etcâ€¦ I will never use acrylic when I may also need epoxy? Iâ€™d never use Epoxy when it can crack? Everyone knows that epoxy is hard and brittle. I just seal it up once and be done with it forever (using 1 system - no weak links).

I was able to purchase a huge fiberglass tub dirt cheap ($25.00) because it did not have a bottom. I simply cut a piece of plywood to drop inside it, used Sani-Tred products to seal the plywood and to seal it to the fiberglass tub. Iâ€™d show some pics but the tub has coral base and wouldnâ€™t do much good to show that. I had some left over and used it for other small apps.

I'm not bashing ANY ideas, the use of the acrylic was "an idea" and that is precisely what this forum is about. I'm just giving my 2Â¢

areze

02/21/2006, 11:45 AM

do you have to bring it to a vendor for them to spray the product into the tank? or can it be done at home?

its flexable and wont crack as well?

smooth I assume, so bulkheads seat properly?

JC Pollman

02/21/2006, 11:50 AM

My understanding is that it does not hold up well under UV. Do you put a coating of anything over the top?

areze

02/21/2006, 01:21 PM

why would there be UV in a fish tank? UV is harmful to fish and humans. bulbs should be UV shielded. and UV filters should be completely sealed.

huig

02/21/2006, 01:32 PM

hi
check out the site for Royal exclusive, those guys build enormous tanks with plywood and pvc. be sure to use an additional piece of pvc to make the surface of the bond larger and thus stronger.

JC Pollman

02/21/2006, 03:39 PM

Sanitred replied to my email on how to use it for a plywood tank:

Plywood Aquarium:

1) The first thing you would do is prepare the substrate. Make sure the substrate is clean, dry, free of any previous applied product, and foreign matter.

2) Prime the substrate with 1 coat of PermaFlex (240 sq ft per gal).

3) Patch and profile any plywood joints, seams, cracks, holes, etc... using LRB/TAV mixture at a Â¾â€ bead. This mixture is mixed 2 to 1, 2 parts LRB to 1 part TAV.

4) OPTIONAL but very much worth while. You would want to apply a coat of LRB (Liquid Rubber Base) to the interior of the tank to create â€œlike a thick membraneâ€. I would apply it at approx 80 sq ft per gal though LRB can be applied at any thickness. The LRB membrane will overwhelm any imperfections within the plywood, guarantee an absolute seal, allow ultimate flexibility, and durability.

5) Topcoat using 1 coat of PermaFlex (240 sq ft per gal) if you are not using VHO lighting, metal halide lighting, or any other high UV lighting.

If VHO lighting or any other intense UV lighting will be used, Step 5) can be replaced by applying 1 coat of a good 2 part epoxy paint (NSF approved ideally). This paint will give you the color desired and extreme UV resistance. This coat will not aid or inhibit the waterproofing/sealing of the system.

areze

02/21/2006, 04:49 PM

hmmm that sounds roughly the same as any other epoxy, infact with the exeption of the optional liquid rubber base, for almost any tank except for T5 lit I guess they suggest you do use the same epoxy... and your back to the potential joint cracks and all that such stuff. except for a thin rubber gasket that I cant see holding up long term if the epoxy cracks and its exposed to salt water.

RandyStacyE

02/21/2006, 05:12 PM

Sani-Tred products do not break down under long term UV, it is just not permanently "color fast" under long term UV (in other words it will fade in color). That is the only purpose for the paint coat.

Their life time warranty is regarding the products "performance" to never bubble, chip, peel, crack, delaminate or leak for the life of the tank. I asked them and it only makes sense - how can they be at fault if I miss a spot (hence the purpose for the membrane - you can't miss a spot). They said I don't even have to use the membrane but I only wanted to do this once.

I've done this before, the prime coat of PermaFlex will absorb into the wood therefore you get a permanent bond.

Patching the seams (LRB/TAV mixture) will molecularly weld to the first coat.

The LRB membrane will weld to it all while creating a thick impervious, permanently flexible membrane.

PermaFlex topcoat if NO UV lighting ~ or ~ Paint if you have extreme UV lighting

JC Pollman

02/22/2006, 05:59 AM

This sanitred is sounding very interesting. My current tank is plywood, and I used the 2 part epoxy on it. The tank has a few problems, so I am in the planning stage of making a new one. My thinking right now is to build the tank out of plywood, frame the tank with 1/4 inch thick angle iron to give it strength, and then give everything a thorough coating with sanitred. The iron should be more than strong enough to hold it together, and if it is coated, there should not be any chance of rusting.

Thoughts?

bmcelhinn

02/22/2006, 12:28 PM

It doesn't work, I tried it 3 years ago.

I built a 240 gallon tank and used the best wood, $100.00 per sheet. I used epoxy to line the entire inside of the tank, then I lined it all with 1/4" acrylic.

The tank held water and lasted for 3 weeks. I didn't bring it inside because I wanted to test it first so I had it sitting outside. The wood and acrylic expand and contract differently so eventually after a few weeks the acrylic started to crack. Eventually it cracked and the the water all spilled out all over, not pretty.