Agree that light up-grade can / does cause algae bloom......they should be cut back then increased slowly until desired lenghth is reached....also.....what are your tests looking like? do you top-off with tap water or ro/di.........post as much info as possible
type of lights
wattage
duration
type of top-off
chemistry(ammonia/nitrite/nitrate/ph/temp
phosphates(if you test for them)
the more info you provide the easier it is for folks here to offer help and advise
and welcome to the board....sounds like a nice syatem you have set-up