Unfortunately if you have algae before you install the scrubber, it takes a month or two to make a dent in it. Just keep up with your water changes and maintaining your scrubber, I still have a few nuisance patches that are driving me nuts.
Sure, depending on the amount of algae you have and if you have herbivore fish...but the alternative is more algae.:D
If you could say to yourself, I'm going to install this thing. In less than a month my algae is going to stop growing, and shortly after that I'll never have algae in my tank would you do it?
Of course you would.