Going to the local fish store and checking you water will just be chasing a dragon. I have some very good fish stores in my area, even some that are supposed to be plant experts and they are no help with a high tech aquarium. When I had this issue I went to a six hour photo period and in a few weeks every thing cleared. Give it time and only change things one at a time, every few weeks or so. Remember that it is never too much of anythings that causes algae but not enough.