I keep reading so many posts about hair algae. Most people don't believe me but a tank with algae is usually much healthier than a tank with absolutely no algae. If my tank has no algae I worry and know something is wrong. It grows on all healthy reefs in the sea, that is why there are more herbifores than other fish. At night a healthy reef will be covered in urchins and slugs. That is why those animals are there.
(Diving at night is completely different from day time diving)
Some schools of tangs number in the thousands and they visit the same areas every day. At night urchins scrape the rocks so well that they wear away some of the rock, but algae is so tenactious that it re grows enough by the next day to again be mowed down.
Algae is viewed by many people as a disease or curse. If it were not for algae there would not be reefs, reef tanks or us.
Algae is the perfect water purifier much better than all the phosphate and nitrate removers we use in tanks. I personally never used any of those products, (sorry sponsors). If you dive you will see algae in all the nooks where tangs can't get to. At night baby urchins usually take care of that but if you go to a tropical tide pool right on the edge where the water meets the rock you will see it is covered in algae. Usually with Sally Lightfoot crabs all over it because they are one of the only tropical intertidal animals that are adapted to eat it.
When I dive in the daytime I am in awe at the number of surgeonfish and at night the horde of urchins that you have trouble seeing in the daytime.
I see that the first thing people do to eliminate algae is change the water, does that ever work? Not really. It actually will prolong the growth.
If you have a large bout with hair algae the water is very clean with no nitrates or phosphates because it is all tied up in the algae along with any iron, another essential algae nutrient. Why would you change such perfect water?
We as captive reef keepers can not rely on animals to eliminate algae because the nutrients will just be re cycled back to the water, we need to remove the nutrient laden algae not the pure water. You will notice that it only grows so much then stops. It never grows out of the tank and up the walls, thats because it exhausts the nutrients then stops growing instantly.
What happens next is that some of it dies, usually the algae that is in the darkest places where it is harder to live. The dying algae release their nutrients allowing more algae to grow.
Algae removes these nutrients very fast and changing the water will not help.
But there is things we can do because we don't want the stuff covering everything, just a short growth on some things is fine.
It can not live in a tank where it has absorbed all the available nutrients. Now the secret is as soon as the algae starts to die we suck it out. It will lose it's ability to "stick" to the rocks and it could be blown off with a canister or diatom filter then it must be removed. Some of it could be physically removed by hand with the help of a tooth brush.
After a few days it will be gone and you can change water, go out to dinner, watch "The Real Housewives of wherever" or do anything you like.
Of course this only works for a heavy infestation, a litle hair algae is no problem.
Now you should have some herbifores, slugs and urchins to keep it short. When the tank is in equilibrium the herbifores will keep it under control but they will not help at all with a tank full of hair algae and you are wasting your time using them.
Allowing or forcing it to grow someplace besides our reefs is the best long term solution because we get the benefit of having algae in our system but we don't see it.
A lighted refugium is really the answer.

I think the Algae gives a nice natural look, it's only when it goes out of control and spreads to much but you can pick up loads of very beautiful fish that keeps it under control, I like the mixture of the rocks colours mixed with the purple and green.

I like a bit of algae too, I agree it is very good at cleaning the water. I think the reason people suggest a water change is because an explosion in growth is often a sign that the water is not clean so a water change would make sense. What i don't understand is why people try to get rid off all the algae without fixing the imbalance, killing the algae will just make the problem worse.

My display tank is kept pretty much algae free due to some star fish and snails, and one very active urchin, as far as the 90 gallon sump running downstairs...i haven't been able to see through the glass for a long time. My tank has never been better!

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I believe you.

does that mean I am not a people?

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fw leiden since 1979, fo salt since 1979, mixed reef 55g 2002-2009. Strong emphasis on the tank taking care of itself. Balanced with plant life, no water changes, tap water, no filters in FW. Only dosing calcium, alk, mag in marine reef tanks. http://www.aquariumforum.com/f15/my-...ods-26410.html
recent tanks (till 2009) 7 years- 10g FW leiden 7 yrs, 55g mixed reef 7, 2 yrs, 20g FW leiden, 10 g fw leiden , 29g mixed reef, current tank 55g leiden