newbie please advise

[Jevon Yacyshyn]

I cannot get rid of this algae. Every time I clean it out, it will stay clean for approx three to five days and starts to come back. I have taken a water sample to Big Als and they tell me it is clean.

I have a 75 gal tank with 30 gal sump
500 W corallife light
1100 gal pumps (three combined flow)
protein skimmer