Green Hair Algae Problem? HELP me and others alike Fix this

[SpikeJones]

Hey guys making a call out on how to eliminate this eye sore, within our tanks, so others with this problem can learn.

As of right now my live rock is about 20 % green hair algae

My modes of action are...
I bought a PhosBan 150 reactor and am currently running it for 5 days - Probably won't see a change for a while or will I?
Within this topic of Phosban, I was unsure how much Rowa phos to put in the reactor for my tank (which is approx 30 gal) so I thought about a half a cup that probably works out to 50 g. - Should I put more or less?

And will soon be running RO water (yes i know Tap water is bad but it is all i had at the time)

Thanks