I call my ststem a "frankenstein system" because it was stitched together a piece at a time over a three week period from remnants of stuff originally used for something else.

I had an old well aerator tank that serves as the basis for my system. A Home Depot 600 gph pond pump is the water moving engine. Several 3 gallon rubbermaid bins stacked on 1X2's, drilled with bottom holes and filled with an assortment of washable A/C filter, plastic scrubbies, pea gravel, sponges, PVC cuttings and shavings, and old aquarium gravel was the original biofilter and also provides aeration.

I had planned to stock the system with maybe 8 to 10 small tilapia. A friend has oreochromis aureus swarming in farm ponds on his property and offered to castnet me some. He showed up with three dozen ranging in size from 4 inches to 7 inches! This was a massive overload for the size of my system, but I forged ahead regardless.

Naturally, I had sky high ammonia right off the bat. Massive water changes did nothing to bring the levels down. I was using well water and when i tested the well water, I learned it was coming out of the ground at over 4ppm ammonia. I replaces 135 gallons of well water in the aerator tank by hauling canal water up from my backyard canal 10 gallons at a time in two 5 gal buckets. THAT was some work, believe me!

I knew I needed more than 125 gallons to support the amount of tilapia I had so I recruited two 35 gallon plastic trash barrels and a 20 gallon plastic trash barrel to serve as my sump. Nine more double bucket trips from the canal had them filled with clean water.

I had another small fountain pump on hand and some extra pea gravel and scrubbies so I used the little pump to recirculate water through an additional biofilter in one of the 35 gallon barrels and used a gravity feed from the aerator tank into a third biofilter (scrubbies) in the other 35 gallon tank. Both 35 gallon barrels drain into the 20 gallon via gravity flow and I relocated my 600 gph pump into the 20 gallon sump where it pumps into the fish tank.

Within a week, my ammonia levels were zero, but the nitrites and nitrates were sky high. I recruited some wild growing water hyacinth and placed a few bunches in one of the 35 gallon tanks. Nitrates immediately started to come down, but it took another week and a half until the nitrites dropped. Needless to say, I stayed busy humping buckets of water from the canal for daily water changes until the nitrites finally dropped!

Today is exactly 3 weeks since I added the tilapia and for the past 3 days, my readings are ammonia 0, nitrites 0, nitrates between 0 and 5ppm, and Ph 7.4 to 8.0. (The Ph drops when we get rain but increases when I add canal water to the system). Apparently, my system has cycled. Now I'm making WAY fewer trips with buckets of water from the canal (thankfully)!

I was astounded at how much duckweed three dozen tilapia can consume! I've gotta seriously ramp up my duckweed production to keep pace with demand! I'm not very scientific about feeding. Two to five times a day, I add a few ounces (by volume) of BSF larvae and they are consumed within seconds.

Fortunately, my aerator tank has a central drain and opening the valve to drain maybe a gallon daily pulls most of the tilapia poop crud out of the fish tank. That goes into my duckweed bins to fertilize duckweed growth.

My system ain't pretty, but it seems to be cranking along nicely and I am totally amazed to see how much the tilapia have grown in just three weeks!

Not sure i know how to do this, but I'll try and attach a YouTube video of the system and feeding BSF to the tilapia.

http://www.youtube.com/watch?v=DdfI1byL ... e=youtu.be