8x4x3 Plywood/Pondliner/Acrylic Tank

EighthNotch

Feeder Fish
MFK Member
Jul 21, 2016
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So I'm in the planning stages of my first plywood tank and would like your comments, ideas, and advice. I've never put a tank together before but I've built stands for larger tanks etc. and I'm confident with this project. This is my first build so I'd like to keep it inexpensive.

I've seen a build on here that was glued and screwed with the same dimensions with no additional external support, he epoxied the inside, fiberglassed the seams, and it's been up and running now for a while. My version is using extra strips of plywood around the perimeter glued & screwed into place, and overlapping the seams on the corners for additional strength.

I plan on using 3/4" plywood, EPDM pond liner, and a 2x4 foot acrylic viewing window unless I can find something longer for around the same price, 2x6 would be great. The acrylic will be 3/4" and drilled every 2 inches. Pond liner is laid in to the tank, followed by the acrylic window and then using flat-headed, stain steel self-tapping screws (maybe with washers?) I'll screw the acrylic window through the pond liner and into the plywood to hold it in place. I'll probably use 3M 5200 as the gasket and coat each screw and fill each hole with 5200 before screwing in. In my half-assed google sketch drawing you can see I'll have a frame doubled up around the viewing window so the SS screws can bite into it. This acrylic/screw method has been used on plywood koi tanks on other forums with success. It'll look a lot nicer than running bolts through it.

I haven't checked local plastics suppliers, but a 2x4 foot 3/4" cell cast acrylic sheet is very inexpensive and I could get one shipped for 90 bucks through Ebay. I also haven't ruled out Max ACR or similar products, I just want to stay away from fiber-glassing as I have zero experience with it. I'll probably have to epoxy the top brace anyway so it's waterproof. I figured a EPDM liner would be easier to work with. I may cut the liner up and use seam tape to get rid of the folds.

tank3.png

tank4.png
 

Niners4952

Candiru
MFK Member
Jan 17, 2016
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why not go with a glass viewing panel? You won't have to use any screws just silicone. I built my plywood tank 8'X4'X32" tall with a 1/2" thick piece of glass 8' long and 28" tall, its the height that makes you need thicker glass, 28" is about the limit on the 1/2". Been running for 3 months no problems. I used pond shield and momentive 108 silicone to adhere the glass. I used fiberglass cloth on the seams but its is very easy cause you use the pond shield and not the fiberglass resin
 

EighthNotch

Feeder Fish
MFK Member
Jul 21, 2016
42
15
8
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why not go with a glass viewing panel? You won't have to use any screws just silicone. I built my plywood tank 8'X4'X32" tall with a 1/2" thick piece of glass 8' long and 28" tall, its the height that makes you need thicker glass, 28" is about the limit on the 1/2". Been running for 3 months no problems. I used pond shield and momentive 108 silicone to adhere the glass. I used fiberglass cloth on the seams but its is very easy cause you use the pond shield and not the fiberglass resin
Sweet tank...that filtration is mint. I like idea of pond shield I'm just hesitant to try it in conjuction with fiberglass cloth. If it's really that easy then maybe I can be talked into it.

If you dont mind:
Have you had any issues with cracking or pinholes with the pond shield? I'll have to do more homework on the cloth seams but I'm assuming you paint the corner first, lay the cloth in the seam as best you can and then have some sort of really small roller to paint & flatten it all out and work the bubbles out? How much did you thin the pond shield? Last question, how much pond shield did you end up using on that build?

I've just read other threads on here where people complain about the work-time with pond shield and the thick tar-like consistency being really annoying to work with.
 
Last edited:

Niners4952

Candiru
MFK Member
Jan 17, 2016
333
78
46
41
Just go to thier website and watch their videos and go to youtube and watch Joey aka kingofdiy video on how to build a plywood aquarium thats what I based mine on. The fiberglass cloth was very easy. You put the first coat on wait 24 hours sand it, then after you have your pieces cut you brush on pond shield on the joint, apply the cloth, add more pond shield and use a bondo spreader the even it out, it was so much easier then I thought it would be. You can easily do this with 1 1.5 gallon kit, instructions tell you everything, its about $225 but so easy to use. Now with work time, I move quick I was able to do a coat with 1 batch, it did start to get thick at the end but you can easily mix half what you need per coat and do half the tank then mix more and do the other half. I had everything ready and moved quick, had lots of light. Happy to answer or add more pics that can help. I took pics of everything as I went, I will post a build thread once summer ends
 
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EighthNotch

Feeder Fish
MFK Member
Jul 21, 2016
42
15
8
33
Just go to thier website and watch their videos and go to youtube and watch Joey aka kingofdiy video on how to build a plywood aquarium thats what I based mine on. The fiberglass cloth was very easy. You put the first coat on wait 24 hours sand it, then after you have your pieces cut you brush on pond shield on the joint, apply the cloth, add more pond shield and use a bondo spreader the even it out, it was so much easier then I thought it would be. You can easily do this with 1 1.5 gallon kit, instructions tell you everything, its about $225 but so easy to use. Now with work time, I move quick I was able to do a coat with 1 batch, it did start to get thick at the end but you can easily mix half what you need per coat and do half the tank then mix more and do the other half. I had everything ready and moved quick, had lots of light. Happy to answer or add more pics that can help. I took pics of everything as I went, I will post a build thread once summer ends
I definitely want to see your build thread. The more I look into pond armor the more I like it. For a hundred bucks more than a EPDM liner I can get that 1.5 gallon kit of pond armor and instead of a 2x4ft acrylic window, I can get a 2x8ft piece of 1/2" plate glass for just fractions more. I think if I went that route I would change up my design a bit and do an external 2x4 brace. It'll be way stronger instead of layering strips of plywood around the edges and seams.

Back to the drawing board. Thanks for all your info and photos.
 

takagari

Candiru
MFK Member
Jan 13, 2009
221
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Manitoba
Niner that is awesome! I love the stairs... haha.
Did you make a build thread? I can't find a post on it?
Very impressive
 
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