Sorry no one has chimed in with more then "buy more fish to solve your algae issue" but IMO fish is usually the last things I think of to fix algae....
First off do you have a pic of this algae and tank at all? My guess its hair algae and probably related to more light. Algae usually pops up when there is an imbalace of light, fertilizer and available carbon. I would drop your photo period to 7-8hrs, do a 1-2 punch, and see if it comes back. Will take some time to equalize... Was your previous light 6500k color temp? My guess is it wasnt and changing to a 10000k might have a LOT more PAR causing your algae issue or just the fact its a higher wattage. Also, have you try dosing seachems excel at all? That would be another recomendation. Id try daily doses, helps with Algae and the plants. Finally you have to make sure you have the proper fertz to keep the plants happy so they can out compete the algae, but sounds like you may have as you already had this tank running for a while. So probably related to too much light.
Drop the photoperiod and/or raise the lights up a bit