question about hair algae

[Sea Polar]

I have just started getting a fast growing algae on the back glass of my tank. It is only growing along the bottom and mostly on the back with a little on the sides. None on the rock. I noticed this happened the day after I lost two blue chromis in two consecutive days. They were nowhere to be found.

When I first noticed the algae three days ago it was an almost clear thin hazy film. I cut back my MH lighting from 8 to 4hrs. Yesterday is was clearly hair algae and I turned off the MH's after an hour. Today it was worse so I only ran 4x96w PC actinics.

Tomorrow I will go only moonlights for three days and then do 32g water change. Hopefully this will stop the growth and I can start eradicating the nuisance.

My question is: Should I scrape this off the glass before the water change or should I wait for it to die? I don't want it spreading to my rock. I'm open to suggestions if there are better things I should do. Thanks.


155g
3x175w 14k MH's six months old 1-8pm
4x96w Actinic PC's about 1 year old 12-9pm
Temp 80-82
Phosphates 0
Nitrates around 10 (was zero last week before the missing chromis)
Ammonia 0
Calcium 350 low
Magnesium 1000 low
Salinity 1.023 low from playing around with a new ATO system (raising back to 1.025 over night)

Direct links for pics and then click image for full size:

back lower glass
close up of algae

 

[conorwynne]

GHA - green hair algae, increase magnesium above 1400ppm and it will just die in a couple of days. It goes white almost overnight -- syphon out the remains or it will just increase pollutants.

Run phosphate remover too.
Hmm, just googled it for you, and Marc has a page for it:

http://www.melevsreef.com/gha.html

I'm sure I've seen my yellow tang eat the stuff now that I see it listed on his page. I