I had a bad hair algea outbreak a while back. I traced it to tap water, the water that came out of my sink was testing off the charts with phosphates and it just kept building up in my tank via topoffs and such. Got me a cheap lowes RO unit Turbo snails used PhosGuard, and scrubed my rock problem solved. My phosphates are now at .5 which is about normal for a tank.
Heres a few picks of before and after the above methods I used.
Before
After
This is one of my Turbos keeping what pops up in check, because once you get it you got it. Up to you on if it ever gets out of control again..
I added a 5 gallon Fuge also with macro algea to help feed on the phosphates