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Discussion Starter · #1 ·
Hi all, i had asked about plywood tanks before on this forum, but i had to put the projecton hold. and now i am back to thinking about building one.

I just recently moved. and i I have a lot of 19/32 plywood that has been drylok from the making of a vivarium, so i still have plywood. it isn't the best grade it would have to have the voids patch and fiber glassed. But i would reseal the plywood anyway. here is my questions.

If i frame the plywood tank with 2x4 or 2x3 (have a ton of 2x3's that were left at our new house) can i use the 19/32 plywood?

the tank dimensions i am thinking of is 48L x 36W x 18T (add an inch or 2 for height for air, being the glass is from a 55g tank..)

I have read a few tank build threads that say it doesn't matter about the type of plywood as long as it is sealed no water can get into it. and I am thinking that the 2x3 or 2x4 frame will help support the tank and the low grade plywood, the plywood doesnt have holes in it. but it does have voids in the outer layer.

So if i patch the voids and all will it be ok to use it. if not that's fine i'll just hold off on my tank build till after i get my 40 gallon fowlr tank going. i am only asking because if i can use it, it will save me a ton of money, that i can then put into making it a saltwater tank.

thanks for your opinions.
 

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Well, here is my thinking, not engineered:

The longer a tank is, the more strain on the plywood. The top will bulge out. At 4' long, this is not too bad, might work. Maybe a top brace would provide the additional strength.

The taller a tank is the more strain there is on the plywood. The bottom can blow out. I think with a well built box of 2 x 3 or 2 x 4 around the bottom, like a frame, it should be OK.

However, I HIGHLY RECOMMEND going to a site that shows you some examples of size of plywood : length and height of a tank.
google 'build a plywood aquarium' to find specialized info.
 

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Discussion Starter · #3 ·
thanks, yeah i have been looking at sites and youtube to get as much as i can on building them. that's why instead of building it with just the plywood i would frame it with studs to support the plywood. (i know its over kill on a small tank. but most use plywood that is marine or cabinet grade. and dont have to support it for the same size tank. thats why i am asking if i can get by with what i got, if i frame it? I know i can get by with 1/4 glass 18 inches or less thats why i am using 55g tank glass. saw it in a couple build threads where they used glass from a 55g tank.
 

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I don't know what your plan is , but I wouldn't want to build a plywood tank unless it was totally sheathed inside with fiberglass cloth and epoxy.
I mean a really good job , with filleted and taped corners , and the cloth weave completely filled with epoxy resin .
At that point , the plywood quality is less important - It's really just an armature for the waterproof epoxy membrane inside .

You're talking , what - 5/8" plywood ?
At 18" high , it would probably work with just a top center brace , and no additional framing , IF you built as described above .
You could make a complete one piece top plywood rim , with it cut out to leave a center brace .

It might seem funny , but you could get good info on building a plywood tank on one of the wood boat building forums - They at least have a lot of content on glass/epoxy sheathing .
 

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Discussion Starter · #5 ·
I had thought about Fiber glassing the whole inside. But I never fiberglass anything before. and so it something i still have to research on how to do it. I mean i know the basics. but It's always different when you actually do it, instead of reading about it.

Yeah you can say it's 5/8's well its only a fraction off so ain't going to make or break. but i think i would still feel comfortable bracing it with a stud frame. the added weight don't concern me.

Also i was researching last night and came across people who used cement hard board. with dylok. now i have used drylok in the past on a diy 3d background, and know that its fish safe, and my grandpa's pond is cemented and painted with drylok and it is still going strong 12 years later. So i was thinking of going that route as well.

But like i said i am just trying to get a feel of what is possible and all.
 

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Discussion Starter · #7 ·
Wow thanks.. I actually hadn't seen some of those threads before so that helped me a lot. thanks.
 

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Check out Uarujoey on youtube. Google him + "plywood tank". His videos are always very helpful. You can also like his facebook page and post questions on there, he is really good about answering the questions that pop up or pointing you in the right direction.
 

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Discussion Starter · #10 ·
Thanks. yeah i have subscribed to him been a long time subscriber. he does great work.
 
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