I don't know if anyone has recommended this site but check out http://www.sfbaaps.com/reference_barr_02_1.shtml. In it you'll find a list of recommended levels and parameters of pH, kH, Nitrate, GH, Iron, Phosphate, Potassium, temperature, water flow, fish load, lighting. You'll also find suggested Test Kits. Don http://members.aol.com/d0nxd0n/index.html