Q. How do I get rid of hair algae?
A. A hair algae outbreak is usually a sign of nutrient imbalance in the system. The underlying cause may be difficult to determine. If the net input of nutrients (excess food, overstocked tank, impurities in the water source, dead organisms, etc) exceeds the loss, usage, or removal of said nutrients the result is often undesirable conditions. The key, therefore, is to analyze all of the inputs. Begin with the source water. Is it substantially purified or are you using tap water? We are often led to believe that reverse osmosis (RO) water is pure enough. Not necessarily true. Many factors affect an RO systems output quality.

Secondly a thorough test regimen should be performed. I recommend keeping a thorough log of test results and maintenance tasks. Do not discount the test results if they come in "acceptable". Defining acceptable is not always an easy task. Each tank often has different acceptable parameters. So just because our nitrate and phosphate tests show good does not mean we do not have a problem. Often the algae "fixes" the nutrients as they are produced thereby leaving little to be tested. If you have an algae problem you most likely have a nutrient problem.

To control or remove the algae the nutrients must be limited. Ensure that the water source is as pure as need be. Limit the food, but don't starve your fish. Reduce the bio-load or stocking density of the tank. Make sure the protein skimmer is adequate and properly adjusted. A skimmer should be cleaned regularly for optimum performance. Herbivorous animals should be included in any marine aquarium to control the growth before it becomes a problem. Examples are: tangs, some blennies, some angels, hermit crabs, snails and the like.

Thirdly, check your lighting system. Are the bulbs aged beyond their ideal Kelvin or color spectrum? Our eyes often do not notice the downward shift in spectrum which can ultimately lead to redder wavelength becoming prominent which can stimulate algae. Most bulbs will not effectively last beyond 8 months. Check with the manufacturer for specifics.

It is important to have adequate water movement in the aquarium. The surface of the water should be rippled and slightly agitated. This helps off-gas any excess Co2 that can accumulate which is an excellent fertilizer for hair algae. This is an area that is often overlooked by many.
Another often overlooked contributor of excess algae is trace elements. You cannot assume that because a trace element is good for your tank, that it cannot be potentially bad for your tank. Practice moderation in dosing, especially if there is an algae problem.

Steps to solve the problem:

1. Boost your alkalinity to 3.5 - 4.0 meg/l and maintain it.
2. Check your bulbs.
3. Ensure you have enough herbivores.
   
4. Evaluate your skimmers performance. Don't be fooled by manufacturer's claims as to skimmer ratings.
5. Evaluate your stocking density - do you have too many fish?
6. Ensure your water source is pure. Use distilled if necessary.
7. Turn off all lights for three days. This is somewhat of a desperate situation, but can be effective if caution is taken to check ammonia levels, etc. should it rise as the algae dies.
8. Utilize kalkwasser. Well mixed kalkwasser has been proven to precipitate out phosphates. It also helps maintain alkalinity.
9. Ensure that you have ample water circulation and surface agitation.
10. Be patient and remember good things happen slowly