Backyard Aquaponics
A place to discuss aquaponics

Is there any rule for what height you should put a venturi drain at for a CHIFT PIST system. I am about to start drilling holes in the school tanks and don't want to screw it up. It is a 5000 litre tank with 500 litre sump and six of Joels GB's. I was thinking of drilling though a 40mm tank flange with the base of the flange being 200mm from the top. This would give a capacity of around 1000 litres above the base of the venturi drain pipe within the FT.

What..?????

I'm afraid I don't understand what your doing there...

Why drill a hole? Sketch required I think.

OK, I think I get it now, but I'll post on the main thread.

+1

Here is a picture, I have posted a response to Joel's in the Westfield Primary School thread and would be really keen to hear of others opinions and ideas, seems I might be making up my own rules for CHIFT PIST volumes and operation, hope I can pull it off .

Cheers,
Mike

The height you put it must be higher than the GB, the higher it is, the greater the flow rate.
Otherwise you put the drain at the height you want the FT to maintain minus a little bit.

Looks good to ,me the only suggestion is make the pipe from the ft to GB 90 mmany think smaller you are wasting your time

+1 pipes can't be too big.

The overflow location will have to be much lower in the fish tank than if it were an unrestricted overflow from the FT. I had just two 90 degree bends once from the FT to a sump and the FT nearly overflowed. With as much restriction as in your diagram the water level in the FT will be much higher than the drain level unless the flow into the FT is very low.

Burnsy

Why the drop to ground level from the FT? It increases pipe length, bends, and pressure on the lower joins. This an access/structural thing?

The sketch looks pretty good.
However...
Do make sure the top of the grow beds is below the height of the water level in the fish tank. Having the grow beds really close to the same height as the top of the fish tank will cause you problems.

And you do want to go with the largest drain plumming reasonable for the gravity drain from the fish tank since water always moves slower through gravity drains than it can be pumped into the fish tank. When you add the extra elbows to make the pipe go down to the ground between the fish tank and the grow beds, you slow the water down even more.

Here is the basic diagram I like to use for CHIFT PIST


The height of the plumbing through the side of the tank needs to be at the desired water level or lower and leave you a little head room above it since minor fluctuations do happen and fish can jump.

and here is another way you could do it.

In my book eather of those drawings above are spot on

Pretty much, all pipework needs to be under the deck, check out the photos in the school section.

I plumbed it today using 40mm so I hope that is big enough, otherwise we will have to revert to a pump in the FT, no problem, it is worth a crack. I plumbed it as a closed ring so that pressure remains constant. We are going to overfill the FT, so it will not be a true CHIFT venturi drain so hopefully the additional water volume above the venturi outlet will give us enough pressure.

Be aware burnsy that this will SEVERELY limit flow. so it is my recommendation that you take your pipe size and double it.

Yep, check the other thread, I have pretty much been convinced that I need to sick a pump on the end of it