Collection: GREEN HAIR ALGAE-SALTWATER

If what you see in your saltwater aquarium is a green, feathery looking mass, it is probably green hair algae. Once green hair alga has a foothold in a saltwater aquarium, it can soon cover everything in your tank if prompt measures are not taken. The cure for green hair algae is the same as the prevention: starve it into oblivion. Green hair algae require not only light but also nitrate and phosphate to survive.

Nitrate can be introduced into an aquarium not only as the end product of the nitrogen cycling process (ammonia/nitrite/nitrate) but also via some brands of commercial sea salts and tap water. Phosphate (PO₄) is a part of life on earth. Virtually every living thing contains some phosphate, and it can enter the tank in many ways. Fish and critter foods, tap water, and carbon are some of the phosphate generators in your tank.

What You'll Need to Test Your Tank

If you have green hair algae in your tank, your phosphate is likely well above 0.05 mg/L, which is considered by many to be the lowest level at which green hair algae will grow. If you have green hair algae in your tank and your phosphate and nitrate tests read low or near zero, the algae in your tank could be eating and locking up the phosphate and nitrate so that they won't show up in a test.

How to Reduce Phosphate

The most common source of phosphate in an aquarium is from the freshwater used for top offs and water changes. In this case, doing water changes to reduce phosphate will only continue the problem unless the water source is changed. There are a few methods of reducing phosphate in your tank:

• Use only reverse osmosis (RO) or deionized (DI) water whether you purchase an RO/DI unit or purchase RO/DI water from a commercial source.
• Purchase and use a good nitrate sponge. Many of the nitrate absorbing materials also absorb phosphate.
• Purchase and use phosphate removing products.
• Use mangrove plants in your system to absorb nitrate and phosphate.
• Consider using the vodka method for reducing both nitrate and phosphate in your tank.

How to Reduce Nitrate

Nitrate will always be something to contend with in your tank. For fast, immediate reduction, you can do a water change, using the instant nitrate reduction method. This will reduce your nitrate at the fastest rate, using the least amount of time and water. This will also get your nitrate down to a workable (10 mg/L) level, but it is only a quick fix and does nothing to remove the source of the nitrate. Siphon out as much of the green hair algae as possible. You will probably find that you will have to use several other methods, many of which are part of a good aquarium maintenance routine to keep your nitrate in check.

• Use only RO or DI water whether you purchase an RO/DI unit or purchase RO/DI water from a commercial source.
• Purchase and use mangrove plants in your tank or sump.
• Check to see if your commercial sea salts contain high levels of ammonia/nitrogen.
• Purchase and use a good nitrate sponge.
• Do not overfeed your tank.
• Siphon uneaten food and other loose material (detritus) from the substrate.
• Perform periodic water changes.1

You might want to consider the long-term nitrate control method, which works to keep your nitrate near zero without any lengthy maintenance procedures. This method uses a specific bacteria, which reacts with the nitrate molecule and a carbon molecule, converting the nitrate into nitrogen gas, which is vented into the atmosphere. By reducing the nitrate and phosphate levels in your tank, your tank will soon be healthy and free of the green hair algae. Many of your tank occupants (corals and other invertebrates) will also benefit from the reduced levels.

• Differentiating Between Good and Bad Green Algae

  

  So, how do you know if the green algae growing in your aquarium are the good or the bad stuff? As a general rule, the good algae is intentionally added into an aquarium via planting in the gravel or attached on live rock. The bad stuff just seems to sort of "show up" when the tank conditions are right for its growth. The bad algae tend to spread and overwhelm the aquarium. Fortunately, there are methods to get rid of the bad green algae while still keeping the good green algae in your system.

• 02of 05

  Getting Rid of Green Hair Algae

  

  A frequently asked question is: How do I get rid of green hair algae? While there are several products on the market that will reduce nitrate and phosphate levels in your aquarium water, which act as fertilizers for algae, experienced aquarists have found that preventing the causes of high nitrate and phosphate makes more sense.

  If you want to quickly drop your nitrate and phosphate (algae fertilizer) levels to something in the reasonable range (under 20 ppm nitrate, NO₃, and 0.05 ppm for phosphate, PO₄), the rapid nitrate reduction water change method will accomplish this in about an hour.

  For those who like to ​plan, long-term nitrate reduction or a coil denitrator might be worth looking into.

• 03of 05

  Is All Green Algae Bad?

  

  Not all types of green algae are detrimental to your aquarium. Many aquarists cultivate some species of the Caulerpa macroalgae in their aquarium or refugium to reduce nitrate, phosphate, and other toxins and as a food source for tangs.

  It is the nuisance type of green algae (microalgae) that can overgrow an aquarium that people find difficult to remove. Being able to identify these algae early on is very helpful in eradicating them from your tank.

• 04of 05

  Natural Algae Eaters

  

  Some several crabs and snails consume algae. For example, the emerald crab is reputed to be an excellent algae consumer. Astrea turbo snails are a good all-around algae cleaner with large appetites. The Sailfin Blenny (Salarias fasciatus) is also known as the Lawnmower Blenny because it devours green hair algae.

  While they may do a great job of harvesting the algae for you, be very careful about adding too many of these critters to your aquarium. The leading cause of death in an aquarium for these animals is starvation. Once they have consumed all or most of the algae, there is nothing left to sustain them, so they need to be fed with foods they can consume.
• 05of 05

  Removing Nitrate and Phosphate From Aquarium Water

  Several products on the market will remove nitrate and phosphate from your aquarium water. Some are filter pads that absorb nitrate or phosphate that can be added into the filter chamber and periodically replaced. Several commercial solutions are available that can be added to the aquarium water to bind certain chemicals, as lowering them in the water will reduce the nutrients available for algae growth.