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I am in the process of designing my first aquapoincs system. Right now the plan is to have a constant height in the fish tank, pump in the sump, media based system. The fish tank is a 300 gallon cube (what are those called?), and the two grow beds will be made of wood with an EPDM liner.


I am planning on flooding the grow beds by using a larger pump on a timer (Laguna Maxflo 4200 - I got it for free, so I am going to try it. Max flow rate is 70 gpm, but it is only a 160 watt pump), and having a restricted drain. What is the best way to build a restricted drain?


I was planning on putting a 4" PVC pipe with lots of holes in it to keep the media away from the 2" PVC drain, which will have only a few holes in it.


Also, is there a certain type of PVC glue I should be shopping for? Is UV resistant PVC resistant enough to leave exposed to sunlight, or should I cover it with something?


Lastly, are bulkhead fittings the recomended fittings to form a water tight seal on the cube and against the EPDM?






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Hi Dave sound like a good system -what did you do with drainage system, I am in the process of designing a rafts system and thinking of trying the SUNLEAVES FILL AND DRAIN KIT"/>

good luck on your system
Easy bulkhead fittings can be made from male and female pvc adapters, the ones from the electrical isle in your local lowes/home depot. they won't have long enough threads to go through a 2x12 but work well for anything thinner.

Oh, and its the same pvc material as in plumbing, just grey.
I will warn against the EPDM and lumber grow beds. I'm in florida and I've had termite damage. The Termites eat the wood and don't realize the liner isn't wood till they get all wet from the leak they caused. I'm currently in the process of converting all my liner beds to 100 gallon stock tanks. Just my warning. If you go lumber and liner anyway, make sure there is no wood path from dirt up to your grow bed.

You can use bulkhead fittings through lumber and liner. I have even used uniseals but that can be difficult.

A stand pipe with some holes in the bottom work fine for the timed pumping and slow drain.
Ken - my system is still not under construction yet, so I haven't finalized the drain for the grow beds. But I will probably just go with my current idea since it is cheap and TCLynx thinks it will work.

TCLynx- Thanks for the advice. I was not planning on putting the wood on the ground. I am going to have the legs of the grow bed sitting on cinder blocks, but I might install termite shields now that you have warned me. They are easy to make yourself, and they could save me a lot of trouble. Thanks for the advice!

Hi David,

On my Rain Gutter system.. I am using pipe end cap drill with one hole to do the restriction just as the water return to the Fish Tank, in your case it would be the sump.

Since you are using a 2" PVC drain,, I would recommend you to use 2" PVC end cap and drill a hole in it. The advantage is you could adjust the drilled holes to control the restriction, and its easily replaced just in case you get it wrong.

On a note about stand pipes. I always like to design them so I can pull them out and add more holes or tape up some holes if I get it wrong. A bulkhead that is a slip fitting would actually be easiest for this but I have used 1 1/2" bulkhead fittings that are threaded and I use some of those flexible pipes with threads on the ends as my stand pipes and that way I can unscrew them to adjust the holes around the bottom and I can even adjust their height since they are made to do that. Just make sure the guard keeping the gravel back is big enough to allow you to access the stand pipe.
Here is a link to an animation on building an AP system using constant height in the fish tank method.
Click on the "start pump" button to see it working.
This is only one way to make a system. I hope this helps.
Hi David, A 300 gal 'cube'....are you referring to an IBC tank, with a metal cage and a drain built into it ? If you are, you may already know.....the white ones are NOT UV resistant, the black ones are.

On the restricted drain, you could add a pvc ball valve outside the GB . They aren't 'too' costly, but they don't 'give' them away either. You would be able to easily adjust the flow. could open the valve all the way, to flush out the drain.
Affnan's idea with the cap sounds good .
TC mentioned a 'slip' type bulkhead for the stand pipe..... You can always add a (slip) bushing and reduce the size of the stand pipe, 'if 'you need a different flow amount..I ended up reducing the size of my 1st stand pipe 2 or 3 times , till I liked the flow.

PVC cement does come in different formulas. The clear is fine for up to 4 inch. The gray(s) are for 4 inch and above..They take a little longer to 'set'.
If your trying to do a repair, once you have water in your pipes. You'll need a different type of cement just for that. Regular cement will tend to wash away with even a few drops of water. Rain N Shine is one brand, don't remember what HD / lowes carries.

The regular white plumbing pvc will withstand the UV's for a few years. It slowly gets hard and brittle. The gray conduit pvc 'has' a UV rating, but it's not 'potable' water rated...go figure
When exposed to UV's, I paint my pvc with a white primer to help lengthen it's life.

I've used the conduit adapters like Richard mentioned, with success. You could try that on the IBC tank.
It might be hard to use a uni-seal on it, only because the wall of the plastic is so thin. It's pretty hard to get the pipe to go through a unisael.
I would lean towards a bulkhead with your wood and EPDM GB's. I use 'economy bulkheads' from Aquatic eco-systems.

Good luck and have fun !
I have used uniseals through lumber and liner before but it is kinda difficult and bulkhead fittings are easier.

I have also used regular clear PVC cement on large pipe but never under any real pressure. All my large PVC pipes only have gravity pressure working in them so the pvc cement is really just to keep leaks from happening or pipes from being pulled apart underfoot.

I have also used that regular clear pvc cement under less than dry conditions. Ya can't use it where water is deep or flowing but I've used it on wet pipes where water was still dribbling or trickling. Perhaps I am playing dangerously but most of my plumbing is under very little pressure. I do use more caution and am more careful when gluing the plumbing to and from pumps, especially big ones with some pressure or high flow rates. For gravity drain plumbing, I don't even always glue it except where it is going to be underground or where I have leak issues.

Sometimes for indoor stuff or aquarium stuff, I'll use silicone instead of PVC cement. It can help avoid minor leaks but still be less permanent. Silicone won't work so well where high pressure might blow pipes that are not cemented apart so I've heard of some people using the silicone and adding a stainless steel screw to keep the fittings from blowing apart under pressure.

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