Plywood tank build

[Kloopsfish87]

Hi all,
I’m looking into building a plywood tank, I have a couple of questions. I have two glass panes left over from a tank I picked up for free that blew apart at a seam the panes are 48”x24” one is 1/2” and the other is 3/8. My thought was to use one as a front and the other as a side pane to fill a corner in my basement. Would a 3/8” pane be thick enough for a 30” tall tank? The tank would be around 50”x50”x30” is a 2” over lap enough for a plywood only build? I would like to avoid using 2x4s to brace the side and back of the tank would one layer of 3/4” plywood be sufficient or would I need to double it up? Hoping some experts can point me in the right direction.
Thank you for your insight.

 

[Brobstfish]

At 30” height, I would lean more towards 5/8 or 3/4” thick glass to maintain a safety factor of 3.8. Alternatively, I would keep the height to 24”, and then you could use your existing glass.
As far as plywood goes, you would definitely want more than a single layer of plywood. With a single layer of plywood you would encounter significant bowing which could stress whichever sealant you use on the wood causing cracks, leaks, or failure. Most people over-build their tanks to prevent issues. A second layer of plywood built as a frame around the tank people have had success with - along with fiberglassing the interior seems. Joey has videos on YouTube using this method. Personally I would use 2x4s and build an external frame, they are cheap and it gives peace of mind. If you don’t like the look of the 2x4 frame it is easy to doctor-up with some thin plywood and trim.

 

[twentyleagues]

Depending on where you put the glass on the tank 1/2" may be ok. If it's at the top of the 30" depth it should be ok with proper bracing. I do agree that 5/8 or 3/4 would be preferred. I'd also at minimum use a second 3/4 layer of plywood as bracing at the edges and in the corners of the build. If you plan on putting the window at the bottom of the 30" then I would not do it.