is the only algae you have issue with the film algae on your glass? 2-3 days worth of cleaning glass (especially using tap water) is normal in my opinion. Heck, even with RO water I was doing it every 3 days or so. I would not worry about it. That's why magfloats sell so well and why everyone has one
Anyway, to reduce it (ie, extend the time you need to clean the glass), you can try nutrient reducing media like those new fangled NP Reducing BioPellets
Now, if you had other sorts of algae growing in our tank like hair algae, bubble algae, turf algae, red algae, etc, etc.. then I would be a little concerned.
Oh, and another thing, is your tank getting direct sunlight? That wonderful yellow sun of ours does a great job of growing algae as well. At least it does in my tank. Again, depressing your nutrients further will help with that if you can't avoid direct sunlight.