Green Hair Algae Problem

[cameraman954]

I have a green hair algae problem, but don't understand why.
I have a refugium with a protein skimmer and a uv sterilizer.
My water parameters are:
Nitrite 0
Nitrate 0
pH 8.3
Ammonia 0
Phosphate 0
Calcium 420
My bulbs are all a month old
I have my light on for 7 hours
I have only a pair a clowns that a feed once a day. Either 5 pellets or a quarter of frozen food. Hardly anything
I use RO water and do weekly 20% water changes with natural sea water that has been filtered and sterilized.
I have 3 powerheads to move the water around.
It's not crazy, just certain patches that I cannot get rid of.

From the picture you can see the bottom base rocks are covered in it. It's a 29 gallon tank with MH. The MHs 7-8 inches above the tank, so it's not directly above it. It's a 150w SPS mid-sea blue HQI bulb. This tank has been running for about 4 years. It's only been a reef tank with mostly coral.
Any ideas?

 

[geoj]

Compare it to Derbesia spp.
Keep dkh above 8 and I would add a $30 Phosphate Reactor run Granular Ferric Oxide, Phosban,and PhosGuard this may take a week for you to see the algae start to loose ground or it may do nothing
Buy a high quality phosphate test kit
Test your carbon for phosphate if you run any
My favorite way is to buy more corals that will over grow an area :jy:

 

[cameraman954]

Quote:
Originally Posted by GeoJ http:///t/390431/green-hair-algae-problem#post_3457583
Compare it to Derbesia spp.
Keep dkh above 8 and I would add a $30 Phosphate Reactor run Granular Ferric Oxide, Phosban,and PhosGuard this may take a week for you to see the algae start to loose ground or it may do nothing
Buy a high quality phosphate test kit
Test your carbon for phosphate if you run any
My favorite way is to buy more corals that will over grow an area

so I bought some PhosBuster Pro and started it today. I added 3 capfuls ( 1 cap for every 10 gallons) Should I do this everyday, or every water change or every month? It says that for every treatment it drops it 1 ppm, but I took my water to 3 LFS and they all said I had no phosphates, 0 nitrates and 8.3 pH. I still added the PhosBuster because I feel thats the only explanation. So what should I do for the next week or so? keep dosing or just do it this one night?

 

[reefkprz]

here's my .02
rock absorbs and releases phosphates, if your having consistent algae problems on just a couple of rocks thay have probably acquired a buildup of detritus inside the rock and have absorbed all the phosphates they can and are now releasing enough to sustain the algae which is consuming it so you do not get a readable level on your test kit, I would removed the rocks and swirl them in a bucket of tank water as well as BLAST them with a power head and turkey baster to knock out as much detritus as possible. this may reduce the source of the phosphates in those local areas and the algae then becomes self limiting, aka once it uses up all the phosphate left in the rock or enough so it stops leaching back out the algae will go away. the phos ban etc may help as well.