Yep, definitely an imbalance between light, nutrients and co2. Your plant mass is also not very dense. What is your target co2 level during the photoperiod. I ran my 125 gal up to approx. 28ppm with no ill effects to the fauna. The lighting was much as Byron describes his and I ran the co2 on a similar pattern to yours.
This is a pic of the somewhat overgrown discus tank:
Mark
This is a pic of the somewhat overgrown discus tank:
Mark
