Call me old school, but proper tank maintenance IMO beats chemicals every time. Not knocking anybody on the phosban or purigen idea, but those are simply bandaids for the real problem IMHO.
First, feeding. Overfeeding is quite possibly the absolute easiest way to establish a healthy algae farm like you've got there. How often are you feeding? Any more then once every other day is overfeeding IMO. Each time you feed, how much are you feeding?
Second, lighting. What kind of lighting do you have over this tank? Is it the factory lighting? I've seen a lot of studies that show old bulbs tend to cause algae... not sure how valid that statement is, but how old are the bulbs?
Third, water changes. How often and how much are you changing? IMO, less than once a week isn't cutting it. Again, thats my opinion. Many people do ok doing them every other week, but I think they should be done at least once weekly even if the test doesn't indicate a need.
Now... This is only my experience. I have NEVER had an issue with algae (except some BBA and Hair algae in my planted tanks, but that was because I wasn't dosing co2/ferts...under control)... I always do a 50% water change every week, I feed every other day, sometimes once every 3 days. Lights only came on when I wanted to see the fish. Ambient light from the room provided plenty for the fish to see.
I do agree with fort that a blackout is a good idea. Do a 50% pwc, cover the tank up with a blanket so that no light gets in. Don't look in the tank for 5 days. Don't ahve the light on. Do a 50% pwc when you take the blanket off. I guarantee you that your tank looks 100 times better after that. But, if you don't change something (maintenance, feeding, whatever the issue is) it'll just happen again.