Larger (to me) system

[Ian Cameron]

Hi all, I have just picked the first crop of Swiss chard and spinach from my 20gallon system. Started the whole shebang in early January. My wife is very excited, me too about the possibilities here. So, have started a larger project outside. A. 8'*4'*12" GB and an old bathtub for fish tank. Now, as we live in a significant side hill, this lends itself to some significant advantages, namely draining the GB. My pump is good for 400gal/hr @ 6ft head. So now, what size pipe should I use for my siphon? I use a 1" for my 20gal system, it cycles fairly quickly but the water quality is good and the plants are thriving so I'm not going to mess with it. So, would a 1" work or should it be increased. My problem is getting bigger bulkhead fittings up here. As always, any help will be greatly appreciated.

Ian

[TCLynx]

A 1" stand pipe for a siphon will probably work in the big system too.

However, will the bath tub be big enough to flood the grow bed without your fish needing to learn to walk?

[Ian Cameron]

That sounds good. I calculated the total volume of the GB at 32cu ft. Gives 200 gal capacity. Add the gravel and things should settle out at about 100-120 gallons. The bathtub is an old cast iron 72' *20" * 30" beast. Heavy isn't quite the right word for this thing. I only want to place it once. It will hold 155gal. So given the normal mishaps that are bound to occur I should achieve a 1:1 ratio.  Do you think this is cutting it too fine for an out door setup?

[TCLynx]

If the grow bed is 200 gallons and the bath tub is 155 gallons, you are actually past the 1:1 (especially since you can rarely fill a fish tank all the way to the rim and expect the fish not to jump out.)

So if you have 120-140 gallons of water in the fish tank and it takes 100 gallons to flood your grow bed, you are getting pretty low on water level in the fish tank during the flood cycle.  You might need to add a barrel or something to help mitigate water level fluctuations or reduce the grow bed size a bit.

Now I like the greater grow bed volume but one generally needs to do something to deal with the water level fluctuations to make the 2:1 grow bed to fish tank work.