Others will chime in with more advice soon, but for starters I'd change the water more frequently; say 30% weekly. I would also advise reducing the time you have your bulbs running since you already seem to receive lots of natural light. Also, you might want to try Purigen.
Sent from my iPad using Tapatalk HD
PIMP #427 - 2 x 2213, 1 x 2206, 1 x Surface Extractor