ALGAE: LIGHTING: PHOSPHATES: SIL.ICATE

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I have a 55 with 90 pounds of rock and a bad algae problem. I think its hair algae but not sure becouse I have never seen hair algae before.
My phosphates are 0 my nitrates are .2 and nitrites are 0. I use 2 50/50 55w PC lights that about 3 months old. Now this is were it gets interesting. I used to get steam stilled water delivered from Absopure, and about 4 months ago I bought a Kent Maxxium HI-S RO/DI unit which removes 99.8% of all silicate. But sence I started to use the unit the algae problem has started. In my thinking it has to be the rodi.
Anyway I have 5 SAlly light foot crabs 2 emerald crabs 5 turbo snail (large ones) and a lawnmowre blenny. And just this weekend I got a Fox Face to help as well. NONE OF THESE CREATURES WILL TOUCH THE ALGAE. The blenny likes to lay in it but won't eat it. The sallys and the snail pick at the rock that isn't covered and the Fox Face is deaf dumb and blind to the whole problem.
Now I have been trying to pick the algae off but it grows right back. I've heard about scrubbing the rock but my rock is stacked and to get the bottom pieces is not possible.
So one; I'm looking for the cause and two looking for a solution.
If anyone has an idea I would more then happy to give it a try. Thank
TTFN

 

[mr . salty]

How long per day are your lights on for?? How old is the tank?? I doubt if it is the RO/DI unit,this is usually used to rid a tank of aglae.How often are you feeding the fish??

 

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Mr. Salty,
I my tank is 8 months old, it has 60 lbs of live sand (fiji) my lights are on from 1:00 pm till 9:00 pm and I feed them one cube of frozen brine once every other day. With the 3 cleaner shrimp, the CBS and the Btittel star there isn't a lot that gets left to rot.
I thougth about cutting the light time down but the corals I have I'm afraid that reduceing the light might hurt them. Mainly becouse it was my understanding that corals feed off the light, and losing a coral becouse of and algae problem is not worth it. To give you an example of the alge problem I would say that 20% of 90lbs of LR is covered in this crap. Now I have a decent size Yellow Leather that I have moved to block the light in largely algae covered area, hoping it will kill the algae. But the area where the leather was my get populated by this algae. What ever you say I should do I'll try. Anything to get rid of this stuff.
Thanks again.
TTFN