How to Identify and Control Green Hair Algae in a Saltwater Aquarium

Differentiating Between Bryopsis, Derbesia, and Cladophora Species

  • 01 of 05

    Differentiating Between Good and Bad Green Algae

    Caulerpa sertularoides
    Caulerpa sertularoides. Photo by Keoki Stender

    So, how do you know if the green algae in your tank are the good stuff or the bad stuff? As a general rule, the good stuff is intentionally imported into a tank via intentional planting or as a hitchhiker on live rock.

    The bad stuff just seems to sort of "show up" when the tank conditions are right for its growth.

    Fortunately, there are methods to get rid of the bad green algae while still keeping the good green algae in your system.

  • 02 of 05

    Getting Rid of Green Hair Algae

    Cladophora vagabunda
    Cladophora vagabunda. Photo by Keoki Stender

    A frequently asked question is: How do I get rid of green hair algae? While there are several products on the market which will reduce nitrate and phosphate levels in your tank, experienced aquarists have found that taking care of the causes of high nitrates and phosphates makes more sense. Curing Nuisance Green Hair Algae is a good place to start.

    If you want to quickly drop your nitrate and phosphate (algae food) levels from sky high to something in the reasonable range (under 20ppm nitrates, .05ppm PO4), the rapid nitrate reduction water change method will accomplish this in about an hour.

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

  • 03 of 05

    Is All Green Algae Bad?

    Caulerpa lentillifera
    Caulerpa lentillifera. Photo by Keoki Stender

    Not all types of green algae are detrimental to your aquarium. Many aquarists cultivate some forms of the Caulerpa type macroalgae in their tanks or refugiums to reduce nitrates, phosphates, and other toxins and as a food source for Tangs.

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

  • 04 of 05

    Natural Algae Eaters

    Blue Legged Hermit Crab
    Blue Legged Hermit Crab. Madelyn Catob

    There are a number of crabs and snails that consume algae. For example, the emerald crab is reputed to be an excellent algae consumer.

    While they may do a great job of harvesting your algae for you, be very careful about adding too many of these critters to your tank. 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.

    Continue to 5 of 5 below.
  • 05 of 05

    Removing Nitrates and Phosphates From Tank Water

    Poly-Filter. PriceGrabber

    There are a number of products on the market which will remove nitrates and phosphates from your tank water.