Here's the cure-all I posted originally way back.
I agree with most of what Nijamini with the exception that the not feeding algea aproach is good and should done, but wont stop a real hair algea prob once the stuff really gets a grip on your system.
If your algea problem is fixed by adding a lawnmower blenny trust me, you dont have a real problem
Here's my algea 101 rant
I'm gonna give you my advise on the nasty hair algae curse. Not everone will agree with me on all of what I have to say but I can asure you I've had a reef up for over ten years and I've been to hell and back with this stuff and I'll tell you what works, for sure, some of the time, part of the time, and non of the time. It is true that hair algae loves phosphates and silica, and ofcourse light, and eliminating or reducing these things will help curb it to a degree, but here's the thing a perfectly healthy reef with good water quality can grow hair algae, especially if your reef has ever had it before. Water changes are the quickest way to get your PO4 under control assuming your using RO water or a water source that has no PO4 in it. Here's the hard part and the part that always makes me laugh when people pipe off and say it, that is, all you have to do is worry about water quality and get it right and the hair algae goes away. Thats a joke and not true! The hair algae that is in your tank stores enough nutrients WITHIN ITSELF to grow at an alarming rate with perfect water readings!!! Dont be fooled just because the test kits read zero! Its like a heart problem, once you have, you dont cure it, you manage it. So, here's my 2 cents on how to get rid of it including all the blatent obvious things that are repeated over and over again. Bigger and longer established tanks are harder to treat than smaller ones.
1) Do water changes ofcourse, but rig yourself up a rigid length of clear tubing to your siphon hose to control and vacuum up all the loose algae and reef dust.
2) To really get a head start take the rocks out of the tank and dip them into a bucket of salt water and scrub the algae off with a toothbrush.
3) Cutting your light time, and reducing your feedings are certainly helpful at least until you get it under control. Poeple say that older lights cause algae, its possible but changing them wont help much.
4) Get or make sure your skimmer is running properly! And replace your prefilter media constantly.
5) When selecting a clean-up crew, be careful not to over do it at first! Its great to have a snail for every gallon like some people say, and I dont totally disagree, but if you put a lot them in and some die off, you've now created more fuel for your algae.
6) Dump in some long spiny urchins, you cant kill hardly em, and they really mow! They can tip things over though.
7) The phos-ban products do help, but their expensive and with all the other factors they alone wont eliminate your algae only help manage it after you've gottin rid of a lot of it. I like the slower acting stuff for a long term preventative measure.
8) UV stearlization is good for some things, but worthless for hair algae.
The bottom line on all this is to get it under control you have to get a little drastic, or you wont get it under control. Then from that point on its prevention. Hope this helps.
