300 gallon plywood build

rotccapt

Candiru
MFK Member
Jun 7, 2009
311
11
48
oklahoma
hi all i am going to be starting a project to build a 300 gallon plywood build. so i have been working on the design for a while and i have just about got it all ironed out but i still have a couple loose ends to tie up. so to start the dimensions will be 72" long 36" wide and 30" deep although the actual water level will be 28 inches. this tank will have two corner overflows to a sump. i am planning on using 3/4 inch ply to build the tank and it will have two 1/2 inch thick windows.

the area i am working on right now is the bracing for the tank. one of the inhabitants will be a western painted turtle so i will have a basking area in one of the corners which will make the bracing a bit odd so it can support the basking area.

so my plan is to have two braces for the tank they will be placed 18 inches off the sides of the tank and will be made out of 1/2 inch acrylic to help prevent bowing between the two braces i am planning on attaching a 3 inch wide 3/4 inch thick board on the front and back walls of the tank between the braces. i will add some pics soon of the design
 

BadOleRoss

Feeder Fish
MFK Member
Dec 28, 2009
1,323
2
0
Virginia

rotccapt

Candiru
MFK Member
Jun 7, 2009
311
11
48
oklahoma
i like how you did your tank i think i might redesign mine a little i will loose some water volume but in the end i think it will be stronger. after all this tank will be in my bedroom so leaks are not an option.
 

rotccapt

Candiru
MFK Member
Jun 7, 2009
311
11
48
oklahoma
hi all well have after some thought i have decided to redesign my tank a bit. the exterior dimensions will be the same but the gallonage will be about 280 ish. so i have decided to make the tank with a 2x4 exoskeleton and 1/2 inch ply for the insides. on most builds i have seen people bild the tank like you would a wall and then sheet the tank inside and out. well for this size tank i think that is a little overkill and i would loose a lot of volume building that way. so i have decided to build my tanks with the 2x4's turned 90* from standard so with the 1/2 inch ply my total wall thickness will be 2 inches since the nominal thickness of a 2x4 is actually 1.5 inches and with the 1/2 inch ply that gives me 2 inches. for the top i have decided to lay the 2x4 flat to create a euro-brace with the 2x4's

i plan of joining the boards using pocket screws

so what do you all think of my design. also do you think i will need a center brace with this tank?

here are a few pics of the rough design
View attachment 757922View attachment 757921View attachment 757923tank 6 top.JPGView attachment 757922tank 6 back.JPG

tank 6 top.JPG

tank 6 back.JPG

tank 6 front.JPG
 

BigDaddyK

Gambusia
MFK Member
Mar 9, 2011
117
0
16
Ontario, Canada
I am concerned with flipping the 2x4's 90 degrees... they have little vertical rigidity this way (they will bow). I like the over all look of your tank but I think that your proposed design is flawed. I don't mean to be offensive in that statement I would just hate to see tank failure for you. I build a 310 gallon and although not comon I laminated 2 pieces of 3/4" ply together to strengthen the tank. thus having 1.5" of wood all the way around. You might be thinking that you will also have 1.5" of wood but consider that Plywood is cross grained... i.e. lay it down one way for the first layer then 90 degree flip for the next piece making it stronger
 

rotccapt

Candiru
MFK Member
Jun 7, 2009
311
11
48
oklahoma
based on some of my research on other peoples tanks i have found a few that have successfully built 300-400 gallon tanks with nothing more than 3/4 inch ply such as this tank found here http://www.monsterfishkeepers.com/forums/showthread.php?443327-First-Tank-Build-400-Gallon

so i figure that if it can be done with 3/4 inch ply my design should work. i will also be using epoxy resin and fiberglass to waterproof the tank so i will also get strength from that.
 

toweraquaticservices

Feeder Fish
MFK Member
Nov 11, 2011
138
0
0
Florida
you are correct. I made a skeleton frame from 3/4 plywood and sheathed it with 1/2 ply, then a layer of 1/4 hardi, and it is SOLID. Even turning it in all directions and pulling it upstairs on a dolly.
 

rotccapt

Candiru
MFK Member
Jun 7, 2009
311
11
48
oklahoma
well i have decided this is the version of the tank i will be building now i just have to finalize the design and see how much the glass will run me
 
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