How do I get rid of this Algae?

[perisse]

Hello, people.
I've had this algae on the display for 3 months now.
Last month I brought a fish without QT and got ICH on the display, so right now I have removed all fish to a QT tank and have only coral, rocks and two shrimps on the main.
I took half the rocks away for a "cooking" procedure to get rid of the algae.
But I had to leave those because I need the tank running and also because I don't want to kill the mushes living on them (is there a way to remove them from the rocks without killing them?).
So, I don't feed for a month. PO4 is 8 ppb according to the digital tester. My RO DI is 10ppb, so i'll stay around that.
Why does this algae keeps growing?
Please help me.
https://lh6.googleusercontent.com/-n_84QrVDwig/TwpZdeiKDeI/AAAAAAAAAFo/emX0P_Qh7Dg/s640/IMG_1718.JPG
https://lh4.googleusercontent.com/-RuT3AF0JiOc/TwpZeIq9c-I/AAAAAAAAAFs/fcPjB8BsIMI/s512/IMG_1719.jpg

[capschamp]

PO4 is one reason for the algae. Run gfo/some type of phosphate remover. You may need to change your rodi filters also.

[capschamp]

http://www.reefcentral.com/forums/showthread.php?s=&threadid=1182318

Check this thread out. Ive used a phosban reactor in the past and it helped eliminate an algae problem. I did not know the media was depleted so fast though.

[aecasasus]

Try to lower your PO4, run GFO and up on the Magnessium.... Pull it by hand and eventually it will fade out.