What are the contributing factors of hair algae?
High Phosphates / Nitrates. These nutrients fuel the growth of hair algae.
Lighting. Flourescent and MH bulbs slowly shift spectrum while improper bulb selection can fuel algae growth from day one.
What can you do to control and eliminate hair algae? (in no particular order)
Harvest as much of the algae as you can by hand. If you pull the algae out of the water you are removing all the nutrients that algae consumed. If you leave the algae in the tank it will eventually release the nutrients when it dies and decomposes, fueling the cycle even further. It will help your frustration level if you think about how nice it was for the algae to convert the nitrate and phosphate into a form that you can actually grab ahold of and remove from your tank manually. It's a lot cheaper than a water change.
Don't scrub or brush the rock when you remove the algae. Scrubbing or brushing the rock will more likely spread the scourge rather than stop it. Scrubbing also will prepare the rock surface for attachment of new algae. It's much better to simply "pull" the algae off and remove it from the tank in one motion, attempting to not let any of the algae float free in the water. If there is still some on the rock, that's ok, you don't have to remove every last trace, it will eventually die off.
Run a skimmer. A good protein skimmer will help pull nutrients out of the water that bad algae feeds on. Reduce your light period. Depending on what other organisms you have in your tank, you can reduce your light period anywhere from a few hours a day less than normal to none at all. Use your own judgement based on your tank. I wouldn't do this until I had harvested as much of the algae from the tank as possible, otherwise you will have a lot of dead algae polluting your tank.
Use a pure water source for all water additions. Using RO, RO/DI, or some other water purification that removes phosphates and Nitrates will prevent you from feeding the problem right from the start.
Water Changes. Water changes can reduce Phosphates and Nitrates but it probably won't fix the problem long-term. You need to find the source of nutrients and resolve the problem at that point.
Replace old bulbs. Always replace your bulbs at the recommended time periods.
Don't use "grow" or plain old bulbs. Grow bulbs tend to have more light from the "red" portion of the spectrum which helps algaes grow but does nothing else for your tank. Get rid of them and spend a little money on good marine bulbs that are the proper spectrum.
Don't let natural sunlight into your tank. Some people have been very successfull at using natural sunlight to light their tanks. However, if you are having an algae problem, then I would stop using sunlight until you get it under control.
Get a good cleanup crew. The formula that worked for me was (roughly) 1 snail per gallon and 1 hermit for every 2 gallons. (In my 55 I put 40 snails and 24 hermits)
Don't over feed. In fact, you should decrease or (some suggest) stop feeding completely. Over feeding can create a surplus of nutrients. Uneaten food decomposes into the perfect fuel for hair algae. A large cleanup crew will help you with this situation also, as they will eat "overfeedings". Feeding less reduces the nutrient "input" into your system, giving the algae less "food". Additionally, not feeding will theoretically induce the critters in your tank to eat the nuisance algae. It's kind of like when Mom said "No dessert before you finish your brussel sprouts."
Grow competing 'good' algae like calerpa, etc. These algae can also become annoying as they can grow very quickly as well. Also, you may have trouble keeping them in your tank if you have fish that eat them. (Tangs for example). A refugium is a good way to grow macro-algae's without letting your fish eat it all.
Another competing 'good' algae is coralline. Be sure your pH, Ca and Alk levels are appropriate for good coralline growth and eventually it will take over any vacant spot in your tank.
Adequate water circulation. Good water circulation is also attributed in ridding a tank of hair algae. Try adding more powerheads to your tank
Clean filters regularly. Be sure to clean any physical filters at LEAST once a week, more often is better. Any pre-filters should be rinsed throughly and any algae removed from them.
Lower water temperature. If you have the capability, lower your water temperature to about 74 degrees. The concept here is that this temperature shouldn't effect inverts or fish, but will stunt the growth of the algae.
Most importantly, be patient. The algae will not go away overnight. It can grow faster than you can pull it, but it recedes very slowly. Don't get discouraged and keep harvesting as often as you can. You will beat it eventually!
