Treat hair algae with darkness?

debbie g

I replaced my metal halides and had a huge algae bloom. I took out many of the rocks and scrubbed off the algae with a toothbrush, but I could not remove it all (At least not without disassembling the WHOLE tank) So the algae came back as hairy as ever. I did try keeping the lights off for about 2 or 3 weeks, no change. So here is my question.... What if I take out every rock that has the algae on it and put them in saltwater in a garbage can with a heater and circulation and keep the cover on tight? Do you think this lack of light would kill the algae but leave the critters alive? If so, for how long should I do this? Also, the rocks that have corals on them, I'm going to leave in the tank. Would the little bit of algae on them eventually spread to the whole tank causing this problem once again? The phosphates on the tank, the water, and the salt mix all come to zero. I just changed the replacement filters including the membrane on my r.o/di. Thanks for any help. This is so frustrating.
Debbie G


Active Member
I've heard of covering the affected areas with thick cloth until the bloom subsides. This would keep you from having to remove the rock from your display. Usually this is a short term issue until the skimmer or phosphate magnet does it's job. Light replacement was your only change? Skimmer still working properly? I had a small bloom after adding LED moonlights and leaving them on 24/7.


What is the kelvin rating on the new bulbs? The wrong spectrum could reek havoc. I would have your local fish store check the phospates for you just in case your test kit may be bad. Have you thought about a lawnmower blenny?

debbie g

socal, If I had to cover all the affected areas with cloth, then I may as well dismantle it. The algae is just covering way too much. Skimmer is also working fine.
Kelly, the bulbs are 175 watt, 10,000 k I believe with the 03 actinics. They are the same bulbs that were in previously, but I hadn't changed them in 2 and a half years so it prob was quite a different kelvin rating than they had gotten used to. And when the tank was new and I went through this, I did get a lawnmower blenny, but once the algae was gone, so sadly was the blenny. But I will take some water to be tested by my LFS. I was just wondering if anyone ever had any success with just total darkness, no scrubbing? Anyone?