First system questions

[Justin McCullough]

So my wife and I have decided to start aquaponics. We are trying to build a small indoor system. I have some questions on our setup. First some specs:

We have 2 GBs - one is a 31 Qt storage bin measuring 26.7x15.8x6.9in - and one 51 Qt storage bin measuring 24.375x15.125x11.75in

We want to grow tomatos, potatoes, onions, lettuce, carrots, cucumber, thyme, basil, peppers, oregano, sage, rosemary, cilantro etc. So first question: Was it a good idea to get a deeper GB for the carrots, potatoes and onions? And then the more important question: How deep of media? 5" in the 6.9" bin and 6-7 in the deeper 11.75" bin?

Next thing is, we want to do channel catfish eventually so we were looking at 40 and 50 gallon tanks. But we have a 20 gallon tank right now with normal aquarium fish in it.

Ok so more questions: If I've read correctly based on about 80 quarts, or GB cap is 20 gallons. So: If thats rightm, should we just use our 20 gallon until we can expand/upgrade to 30/40/50 gallon GBs and get that sized tank?

Ok so now onto configuration. I was thinking auto siphons for both as they'll be on shelves above eachother. Can I get away with just one pump and either use a spliter to feed both or do a fast fill slow drain into the lower GB from the upper and adjust to both siphons to get FT volume every hour?

[Rob Nash]

small siphons with splitter. try for 6" and 11" of media. with 5" and 9" of water depth. i would aim for 5cft of media with a 20 gal.

on the next tank, try a mortar tub ...around 5sft, much stronger, and only about $12.00.

try this link for a bell siphon thats just right for this size beds. http://aquaponicscommunity.com/forum/topics/how-to-build-a-bell-siphon

[Justin McCullough]

Ok I think I'm gonna go with the 20 gallon tank. But I still need to know Can I get away with just one pump and either use a spliter to feed both or do a fast fill slow drain into the lower GB from the upper and adjust to both siphons to get FT volume every hour? 

[Rob Nash]

one pump with splitter, no timer, two siphons, two drain lines back to FT.

[Justin McCullough]

Ok cool, thanks for the advice. So the higher GB is going to be about 4-5 ft higher then water level in FT. Do you think a 100gph pump will work?

Rob Nash said:

one pump with splitter, no timer, two siphons, two drain lines back to FT.

[Rob Nash]

a 180 should do it. 

[TCLynx]

Or one of those little 264 gph pumps that uses only 20 watts should work.  Add a bypass with a valve so you can let the excess flow go back into the fish tank for extra aeration.  The lower grow bed will also need a ball valve so you can adjust the flow at the lower bed and the fish tank to make sure you get enough flow up to the top bed.

For Channel Catfish, I will recommend you wait till you can do a really big tank since I don't think a 40-50 gallon tank is big enough to grow out a channel catfish, I personally won't put channel catfish into even a 100 gallon tank for grow out.  Only for quarantine of new fish when I first get them.  Here is an example why I like bigger tanks for them.