Supports around plywood tank?

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djlancer88

Feeder Fish
MFK Member
Feb 19, 2008
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Syracuse NY
In the process of sealing my plywood tank and after looking at a lot of different ply wood builds I see support going all the way around the tanks, 2x4's, etc. Now my tank isnt that big compared to others but do you think I should have some outside support going around the tank? maybe build a frame? Dimensions are 96"Lx24"Wx19"tall; Also 3/8" thick glass will do the trick right? being so low and all. Trying to keep cost minimal as I am a student

diy tank.JPG
There will be 4 solid supports running across top; going to cut them out of a full sheet of plywood to make a samwhich type look. that one 2x4 is only temporary

diy tank.JPG
 
I don't see a reason to provide outer supports, your tank isn't tall enough to provide the pressure on the walls that outer bracing is needed for. Water depth is where pressure comes from, with your other supports for the top you should be more than fine.
 
Rivermud said:
I don't see a reason to provide outer supports, your tank isn't tall enough to provide the pressure on the walls that outer bracing is needed for. Water depth is where pressure comes from, with your other supports for the top you should be more than fine.
Click to expand...

Thank you for the reassurance on that; Now I just got a price for my piece glass for $234 thats with NY state sales tax included; that is for 1/2" do you think I can get away with 3/8"?
 
Here is a link to a glass and acrylic thickness calculator. It is build with a variable Safety factor rating. Industry standard (recommended by the manufacturers anyway) is 3.8. In our DIY builds with a full support frame as well as structural cross supports you can reduce the SF rating by quite a lot and still be quite safe. If your tank is only 19 inches high (max water depth) then the calculator shows that with a SF of 3.8 you need glass that is .36 inches thick or just a shade under 3/8's. With 1/4 inch glass the safety factor is 1.9. Play around with it a bit, it's a fun tool. IMO you should be using 3/8's glass... 1/4 is just a shade low on the SF scale for me.. i try to stay at 2.2 or better.

http://www.monsterfishkeepers.com/forums/showthread.php?448782-Rivermuds-Glass-and-Acrylic-Calculator-(it-lives)
 
I am a self confessed over builder and I would go with the 1/2" glass. Price the 3/8" glass and see what the cost of upgrading to 1/2" is.

Your tank looks very nice. What is the thickness of the plywood you are using? How are the corner joints constructed? Glass and plywood are very different in there physical characteristics. Plywood will bend a lot... glass won't! You may need extra bracing on the plywood to keep the plywood from bowing when the tank is filled which might cause gaps to form between the glass and plywood.

If your corner joints were constructed well I would not have any concern about the strength of the plywood. I would be concerned about the rigidity of the structure and that glass to plywood bond. A couple more top braces across the top of the tank might add a lot of rigidity to the overall structure.

If it were me I would also add a 2x4 internal frame (glued and screwed) around the inside top of the tank to reduce the bowing of the sides... but I do tend to over build. Because of the clean lines your tank already has I would tend towards internal bracing instead of external bracing... to keep the lines clean.
 
Oughtsix said:
I am a self confessed over builder and I would go with the 1/2" glass. Price the 3/8" glass and see what the cost of upgrading to 1/2" is.

Your tank looks very nice. What is the thickness of the plywood you are using? How are the corner joints constructed? Glass and plywood are very different in there physical characteristics. Plywood will bend a lot... glass won't! You may need extra bracing on the plywood to keep the plywood from bowing when the tank is filled which might cause gaps to form between the glass and plywood.

If your corner joints were constructed well I would not have any concern about the strength of the plywood. I would be concerned about the rigidity of the structure and that glass to plywood bond. A couple more top braces across the top of the tank might add a lot of rigidity to the overall structure.
Click to expand...

the tank is 19 inches tall. the water pressure is not all that great at all. the op stated that they are installing cross braces across the top of the tank. even in standard unbraced aquarium manufacturing 3/8's glass meets the 3.8 safety factor that is the industry standard recommendation. Why would you overbuild even more than it is over built to begin with? the viewing window will be braced with a plywood frame, the top will be braced at several spots with cross beams, and the water won't be any deeper than 19 inches. I am currently running a DIY plywood with 22 inches of water depth and 1/4 inch glass and i am not nervous one bit.. especially since it's been up and running for 3 years now; it is built the same way this is, plywood only with no outside support and 1 brace across the top. the tank has flexed all of 0.0 inches.
 
Thanks Rivermud for showing me the calculator; very very handy tool. Well since I am trying to be cost effective I sent out for another quote on 3/8" thick glass. If the price difference is pretty significant I'll go with the 3/8", If not I'll over do it and go with .50". Thank you for answering and stating facts for the previous post! ;)
 
Oh the plywood Is 3/4" thick I bought the most expensive kind with a nice maple ply for the inside surface; Dont know a real lot about wood, could of screwed myself there lol
 
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