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wireefman
12/19/2009, 02:44 PM
ive been doing some reading on a few sites and i want to make sure i understand what im doing..... first off this isnt a big tank its only a 45 gal cube.... 24x24x18... but my question is for glass tanks you dont want a sheet of plywood with foam undernieth it correct... only want support on the corners of the glass tanks

mdntrdr
12/19/2009, 02:45 PM
Sheet of plywood is fine as long as it is flat.

wireefman
12/19/2009, 02:46 PM
id put a thin layer of foam over the plywood to make sure the tank is level

bglegs
12/19/2009, 05:12 PM
I just used 1/2 styrofoam without plywood...imo just a waste of money for plywood...foam fills in an imperfections...

FearTheTerps
12/19/2009, 05:21 PM
If the tank has trim on the bottom of the tank, you want the trim to sit on a flat hard surface. You don't want to use the foam. The foam will put pressure on the bottom pane of glass, which it isn't designed for and could cause a break. You only want to use padding under a tank when the actual bottom pane sits on the stand. Your tank being a 45g I figure you have the plastic trim on the bottom, so don't use the foam.

uncleof6
12/19/2009, 09:53 PM
If the tank has trim on the bottom of the tank, you want the trim to sit on a flat hard surface. You don't want to use the foam. The foam will put pressure on the bottom pane of glass, which it isn't designed for and could cause a break. You only want to use padding under a tank when the actual bottom pane sits on the stand. Your tank being a 45g I figure you have the plastic trim on the bottom, so don't use the foam.

Wow, good to see someone else that knows the proper use of foam under a tank.

Jim

kgross
12/19/2009, 10:25 PM
If the tank has trim on the bottom of the tank, you want the trim to sit on a flat hard surface. You don't want to use the foam. The foam will put pressure on the bottom pane of glass, which it isn't designed for and could cause a break. You only want to use padding under a tank when the actual bottom pane sits on the stand. Your tank being a 45g I figure you have the plastic trim on the bottom, so don't use the foam.

I still like to use foam to help make sure there are no imperfections under the trim. the only thing is you only use 1/2 inch foam and only cut it to 1 inch wide. Put it just under the trim. It can help a lot with a stand that is not perfectly flat, without putting pressure on the bottom glass.

Kim

Homeytwist
12/19/2009, 11:08 PM
I'll be building a stand next month also and I've given it a bit of thought; my plan is to pick up a sheet of 3/4" MDF (not plywood) that's nice and flat and use that as a top surface of the stand that the tank sits on. BUT, if the stand isn't dead flat (which it won't be), the MDF will conform to that surface and put uneven pressure on the tank corner to corner. So, as a solution I plan to lay down a heavy bead of silicone on the top of the stand, place the MDF panel on top of that, then sit the tank on top of it all and let the silicone cure. That way the MDF panel (being an engineered product) will create a nice solid, flat surface for the tank to sit on, and the silicone will fill the gap between the MDF and stand and allow for some imperfection in the stand construction (which will happen, it's wood afterall!) Of course the MDF will have to recieve a few coats of good quality paint to prevent it soaking up moisture and swelling. The same could be done with a slab of granite which would be ideal if somebody was crazy enough!

30reef
12/20/2009, 12:13 AM
I'll be building a stand next month also and I've given it a bit of thought; my plan is to pick up a sheet of 3/4" MDF (not plywood) that's nice and flat and use that as a top surface of the stand that the tank sits on. BUT, if the stand isn't dead flat (which it won't be), the MDF will conform to that surface and put uneven pressure on the tank corner to corner. So, as a solution I plan to lay down a heavy bead of silicone on the top of the stand, place the MDF panel on top of that, then sit the tank on top of it all and let the silicone cure. That way the MDF panel (being an engineered product) will create a nice solid, flat surface for the tank to sit on, and the silicone will fill the gap between the MDF and stand and allow for some imperfection in the stand construction (which will happen, it's wood afterall!) Of course the MDF will have to recieve a few coats of good quality paint to prevent it soaking up moisture and swelling. The same could be done with a slab of granite which would be ideal if somebody was crazy enough!


If your stand is built properly, it will be flat on top. I understand your concept, but silicone is the last thing you want weight on top of. I personally would not use mdf, plywood has many times the compressive strength. Have you ever seen what happens to a kitchen sink base after a few years of casual contact with water now and then? Even if sealed well, it will not be as impervious to water as plywood.

All you have to do is lay a straightedge across the top to determine if it is flat, if it is flat when you build it, it will be flat when you put a tank full of water on top of it. You have to make sure the stand is sitting on a level surface to begin with.

It is my belief that everyone who attempts a diy stand, builds it without any idea what load transfer is, and ultimately risks a failure. That statement may be a little too broad, but mostly true. There are some nice ones out there though.

Good luck on your construction. :)

Homeytwist
12/20/2009, 02:22 AM
30reef, tahnk you for the feedback on my tank stand concept. I will be using MDF (not particle board as you find in counter tops) due to its manufacturing process which results in a much flatter piece of material as compared to a ply. I agree that a marine grade ply will have much better resistance to moisture, but even that will swell if exposed to a considerable amount of water. And the compressive strength of MDF is far greater than the load experienced under my 24" tall tank so that is not a concern. I may reconsider the silicone in favor of something that is a little firmer (higher MOE), but running some quick numbers the load on the silicone bead once it's flattened out to atleast 3/4" (which it should be) will only be 10psi, so that's probably also a non-issue.

I am wondering though, what do you mean by "load transfer?" I work in engineering, so I'm curious about what you have in mind?

aquaman04
12/20/2009, 06:17 AM
I'm just finishing a 24(w) x 24(L) x 30 (h) stand made of MDF for an identical size tank. I'll try and get few photos up.

30reef
12/20/2009, 11:29 AM
I see alot of photos of diy stands here where the top load bearing surface does not properly transfer it's weight to the sides. It was just recently where a guy had the top supported solely by the screws attaching it.

I did not mean to say yours was built that way. :)

Most are so overbuilt it may not be an issue anyway.

There was a LFS I used to frequent who had alot of custom stands built with mdf, and then sealed and sprayed with Flekstone (sp?), a faux stone paint. They were indeed nice to look at and solidly built, 2 of them I know of had failures due to water compromising the mdf. One of then had the bottom of the stand break out, the other had swelling along the top of the sides.
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To the OP, I would contact the tank manufacturer and see what they want the tank to sit on. I don't see a 1/2" of foam around the perimeter to cause any problems, I use it on my 30g. It compresses nearly flat after a short time.

Homeytwist
12/20/2009, 12:24 PM
Ahh, yes sadly that is often the case... It's not just DIYers doin it though, people will buy inexpensive bookshelves and the like with the shelves held in place solely by fasteners in the ends of the shelves and use that as an aquarium stand :eek1: Hahah, actually my brother had a 25gal on this rickety old end table thing, built just that way. Made me nervous every time I saw it! He's now got my 29gal freshy setup with a proper stand (my DIY MDF unit). On that note, I made that stand out of 3/4" MDF, primarily glued construction, with a double thickness laminated top panel (total 1.5" thick MDF surface). Has 1 coat of primer, 2 coats of quality latex Kitch & Bath paint (actually 2 more now since it's changed color!). Has been in service for a good 5 years, had water splashed all over it, some of which has sat till its evaporated. No issues with swelling or any structural problems over time. I've attached a screenshot of its model (strangely I don't have any photos of the actual stand, only the tank on top of it!), though as you'll see it's a fairly simple design so it's pretty easy to ensure a good seal on all edges and faces ensuring that the water never makes it to the base material.

For fun I've also thrown up a screenshot of the stand I'm designing for my new reef setup. It'll be made out of a combination of veneered ply and 3/4" MDF, with material placement based on its aesthetic and structural properties. It's pretty tough to see exactly how it's built from that shot, but I can provide more info if anyone's interested. Enjoy!

iwishtofish
12/20/2009, 08:01 PM
Ahh, yes sadly that is often the case... It's not just DIYers doin it though, people will buy inexpensive bookshelves and the like with the shelves held in place solely by fasteners in the ends of the shelves and use that as an aquarium stand :eek1: Hahah, actually my brother had a 25gal on this rickety old end table thing, built just that way. Made me nervous every time I saw it! He's now got my 29gal freshy setup with a proper stand (my DIY MDF unit). On that note, I made that stand out of 3/4" MDF, primarily glued construction, with a double thickness laminated top panel (total 1.5" thick MDF surface). Has 1 coat of primer, 2 coats of quality latex Kitch & Bath paint (actually 2 more now since it's changed color!). Has been in service for a good 5 years, had water splashed all over it, some of which has sat till its evaporated. No issues with swelling or any structural problems over time. I've attached a screenshot of its model (strangely I don't have any photos of the actual stand, only the tank on top of it!), though as you'll see it's a fairly simple design so it's pretty easy to ensure a good seal on all edges and faces ensuring that the water never makes it to the base material.

For fun I've also thrown up a screenshot of the stand I'm designing for my new reef setup. It'll be made out of a combination of veneered ply and 3/4" MDF, with material placement based on its aesthetic and structural properties. It's pretty tough to see exactly how it's built from that shot, but I can provide more info if anyone's interested. Enjoy!

What kind of tank would go on the bookshelf-style stand in the pic on the right? If it's a rectanglar glass tank, how would the corners of the tank be supported?

Homeytwist
12/20/2009, 08:25 PM
Iwishtofish, the stand on the right was built for a 29gal rectangular tank. Not sure what you mean by "how would the corners of the tank be supported". If you're wondering about the lack of support directly under the back corners, then I relied on the strength of the 1.5" of solid material to support them. The stand is very solid, no worries about structure on that one.

mdntrdr
12/20/2009, 08:31 PM
MDF and moisture,,,,,Bad combination!

uncleof6
12/21/2009, 03:15 AM
MDF and aquarium stand = Recipe for disaster. You build the "flat" into the stand, not make the top flat on a twisted or otherwise out of wack support rim under the top. You do not use foam of any type, thickness, or just under the rim-- to solve a problem with the stand top being out of wack. It does not matter the size or load of the tank. if the stand is twisted, the foam will twist, and the tank will twist and break. Way too much of this http://i655.photobucket.com/albums/uu274/uncleof6/sheepaid.gif going on with stand building, and the use of foam. The foam serves one purpose: To alleviate point stress, when the bottom glass panel is in direct contact with the stand top. All other uses are against the manufacturers recommendations.

MDF, will expand, rot, and whatever else it feels like doing, regardless of what you paint it will. You can build a stand completely out of 3/4" plywood, as long as the load is on the vertical panels, but I would not trust a fishbowl sitting on MDF.

Corner support: There must be load bearing, vertical support, directly under the rim of the tank. Most importantly the "area" of the corners of the tank-- the area being within 4" of the corner. If using 2 x 4 lumber, the vertical 2 x 4s should be directly under the top rim of the stand. The top rim should be identical to the foot print of the tank. The PLYWOOD top sits on top of the top rim. The top rim must be sqaure, plumb, and level. The corners of the top rim must all be on the same plane. This is why many have trouble building a good stand: It is not easy to do without having cabinet making skills.

Jim