Derbesia (Green Hair Algae) – How to Solve It?

Invasive algae Derbesia and Bryopsis have always been a big problem for marine aquarists. They are able to take over the aquarium very quickly and dominate our corals.

The most popular methods of fighting algae may not work this time. Due to the resistance of these algae, decisive action is needed. If typical methods of combating algae do not work, it may be worth reaching for preparations in which the active substance is Fluconazole. It’s a substance that only fights Derbesia and Bryopsis. Good news is that it’s impossible to fight other algae with it.

Fluconazole stops the growth of these algae by blocking important enzyme pathways and disrupting the integrity of their cell walls.

However, the substance may have a negative effect on calcareous algae, so if you have a refugium in your aquarium, you should pay attention to it.

When starting the treatment, it’s recommended to turn off the skimmer. After about 72 hours, when the algae has already started to decompose, the skimmer can be put back into operation.

The results will be visible after 10-14 days. However, after 2 weeks of therapy, a 20% water change should be performed.

After the water changes are made, the algae reactor can be restarted.


Fighting this type of algae can be very difficult, but using Fluconazole in the right way can deal with them, and thus help our aquarium. After the treatment and several water changes, our aquarium will return to normal.

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