Starting my aquaponics system, stocking ratios and different sized tanks

[Alex Madgar]

Hello guys! This is my first discussion, and first attempt at an aquaponics system. So I totally understand that the first thing every body is going to say is that: Im starting to big, scale it down and experiment first. A couple reasons Id like to start with the system explained below is that I already have the large tank, and the idea of utilizing it is stuck with me now. Also id rather not waste the efforts of setting up a small version then rebuilding for the tank I have. We also have a very large warehouse space that isn't being utilized which would be perfect for a system.

Im new to this and have a few questions. What I want to do is, use my 1500 gallon portable firefighting water tank, get one 275 gallon and one 330 gallon IBC tanks, and a 4ft x 24ft x 1 ft grow bed made of braced wood and a pond cover. For Tilapia, would the sizing and ratio work to grow small fry size in 275 g IBC, fingerlings in the 330 g IBC, and Juviniles or adolescents in the large tank to grow then harvest? Im trying to make it so I can transfer them to the next tank as they get bigger so I can cycle shorter harvest times. Could I flow water between all three tanks and then my outflow to the grow bed would only come from the big tank? Since my grow bed is really long I plan on having a couple different bell siphons on each end with two separate sump tanks underneath. The sumps would connect and lead back to the big tank.

For the tanks being used on the immature fish, would that be big enough to eventually stock the big tank as they grow? How many fish do you think I can stock in these sizes? I read that stocking should be about 1 pound of fish for 5-8 gallons. Im not sure if that is meant for what they will eventually be at adult size or current size. Using this type of "cycling for fish size" does anyone know a good way to move them from tank to tank without stressing them out too much?

and would the sizing of the grow bed be adequate or should I make that bigger? Thanks, I look forward to hearing suggestions!

[Alex Veidel]

The 1lb per 5-10 gallons rule of thumb refers to their current size. Also, make sure you run your water to the fry, then juveniles, and finally adults. You want the fry to get the cleanest water, since they're the most sensitive.

[Jeff S]

If it's possible to partition your 1500 gallon tank into equal compartments that's what I would do. That would accomplish several things: 1. You would never need to transfer fish 2. If you have 200 fish per tank the gallons per pound can be shared between the various sized fish  3. you would only need 1 sump tank, 1 pump, 1 heater, 1 air pump, 1 filter (or set of filters)  4. Water testing and maintenance is only 1 tank. I'm sure there are other benefits too. The compartments would be flow through but be able to contain the various size fish.