Backyard Aquaponics
A place to discuss aquaponics

HI Folks, since I am a cheapa$$ here's what I was thinking...
I want to make a large grow bed and large fish tank but am unwilling to pay the money for it. SOme ponds and large containers can be expensive.

So I though about contructing both with wood and then waterproofing it with paint or epoxy. It makes sense since you could make is any size and shape you want. Then it would be easy to make a stand also out of wood.

THe question is has anyone ever tried to waterproof wood for a fish tank or growbed? Does anyone have any input or experience?

Thanks for the help!

HN

You would be better off making it out of wood then using a pond liner to waterproof it IMHO

Hi HN:
Is pondliner or plastic too expensive for you? You can do a lot with plywood and pondliner, or with dug holes and pond liner. It seems a bit steep at the one landscaping place I priced it at here, though.

I think the big wine or beer casks cut half-height would make good fish tanks unless they have something used in them that is bad for fish.

I also keep thinking about the 70s-style wooden hot tubs; those would probably work well.

That said, people here are using used bath tubs for grow beds and TT is using a hot tub for a fish tank. If you can source them used that may be a good option.

Water weighs a ton, literally - any wooden structure would have to be built like a crap brick house to hold the weight; by the time the structure is reinforced enough you would probably be better off with a fiberglass or plastic container.

You have a lot of boats around, yes? Murray is a boat man and makes custom grow beds and tanks from fiberglass. Maybe the local marine industry has something used that can be adapted for AP.

HTH

Thanks guys. I thought about pond liners but a paint or expoxy seems so much more neater and tight. Plus liners are expensive.

Dave, thanks for the thought about the marine industry. I will look into that.

HN

Yep I agree with you Mon , epoxies can be for potable water, but, the cost of the liner would be cheaper than a kit of food grade epoxy.
Also there would be issues with the joins since epoxy is not flexable.
IMHO.
C1

I myself am using plywood grow beds and have lined them in two different manner.

I made two identical G Bs out of 3/4 inch plywood. The dimensions are 3' wide x 8' long x 1' high. by doing that, I was able to buy 3 sheets of plywood and make both with little waste.

1. The first one I got a non toxic roofing paint, painted the wood and while it was still wet applied cheap polyester cloth covering all surfaces. The material stuck well to the wet paint. Immediately I put another coat of paint taking special care to get the corners coated well. When it was dry, I filled with water and got no leakage and it has been working that way for 4 months. Total cost for this one was about $60.00 USD

2. The second GB I simply purchased a heavy mill black plastic at the hardware store. I trimmed it so it would flop over the sides to protect the outside of the GB from rain. I ran a bead of silicone around the edges of the wood so it would stay in place. I had a small leak when I filled it around the auto siphon but in a few days it "healed"

Cost was $40.00 including wood.

Both GBs are working well and the plastic was much cheaper. I would do it again with plastic.

I would definitely use pond liner for a fish tank and you would have to strengthen the sides of the tank for fish. I can get pond liner for 5.00 USD per square meter here.

A wooden fishtank would be feasible if it was somewhat buried to help support the bottom of the sides. All the pressure is down and out at the bottom.
I think if you built the wood with a close enough fit, then sealed all seams very well, then epoxied it may work well. Perhaps using interlocking cuts of the wood(woodworkers, what is that called again?) and strong wood glue would help.
A little while ago I believe Veggie Boy posted a link to a document outlining making a circular wooden tank from thin plywood and steel strapping rings. Even in a square shape, if it is framed in well using a continuous reinforcement, it could be strong...just over do the reinforcement.
The negative I have found with pondliner is that in order to make corners it must be folded. Inside these folds some wastes can accumulate. I recently opened my lined wooden tank and exposed the closed folds....STINKY!!!!
I think it is better to not have this area of stagnation if possible.
So, a wooden tank can be feasible. How much water are you wanting to hold?

My fish tank is 4m*1.2m*1m made with 15mm pine plywood on the sides (bottom is just a piece of cement sheet to protect the liner against puncture). The frame is two rectangles made from 3"x1.5" OB green hardwood with lap joints in the corners. I used 1inch steel strapping around the corners.

the liner is 1mm pvc pond liner. It holds 4.5kL (4500kg). I would suggest you don't try epoxy sealer - hard work and more expensive. Liner also copes with gaps in the sides.

It bows a little in the middle, but has survived a year now. I would suggest a more square shape unless you (as I did) have a funny shape to put it in. 15mm ply bends fairly easily - a circular tank would be quite straightforward.

I checked the base for rot and leaks recently - no sign of a problem yet.

I am looking at maybe a 100-200 gallon fish take. The gowbed would be smaller, maybe 50 gallons.

The question with pond liner is how do you make the area around the drain water tight?

Keep it coming!

HN

If the pond liner is PVC then it can be trimmed to fit and glued together. Just leave enough when trimming for the seam. There should be no wrinkles unless you have a wierd shape.

Drain hole? what drain hole. I just put a submersible pump in there on a stack of bricks.

You can buy hollow screws with flanges and rubber washers that you tighten around a hole.

I am talking about the drain in the grow bed. How do you make it so it won't leak?

Hi Hn
It just so happens that that Dr Jim Szyper at the university community college of Hawaii published a great manual that you can get free online called " Backyard Aquaculture in Hawaii" it was published in 1989 and amongst other things shows howto build substantial plywood tanks , the whole manual makes a fantastic read and i wouldnt be surprised if the longterm Ap'ers werent familiar with it.
Good luck
TimB

That actually was easy. I drilled the hole in the wood so a PVC pipe would fit tightly and then lined the box. I made a small hole in the liner (smaller than the pipe) and forced the pipe through the hole taking some of the liner with it.

Then I sealed it with PVC cement and a coating of fish safe silicone. Works great.

HN... heres the article...

http://nsgl.gso.uri.edu/hawau/hawauh89001.pdf