It's probably pretty simple - you drastically increased the light over the tank, but didn't increase the corresponding macronutrient levels (CO2, Nitrate, Phosphate, Potassium).
One of these macro levels are probably high (evidenced by the algal bloom) but at least one of the others is low. My guess would be CO2 and potassium.
Are you supplementing CO2 or Potassium?
- Sam P -
plantedtanker in limbo - all tanks currently in storage