alkalinity and green algae

[JudyK]

I have a 72 reef and a 55 fowlr. I've been fighting green hair algae in the 72 for a few months. My alkalinity has also been low. Is there any relation between the two problems?

[Glove]

The low alk isnt causing the algae if thats what your asking. Raising your alk will help to burn out the algae- it may not make it go away completely though.

Alk should be maintained and kept at a desirable level- 3-4meq/L

[Randy Holmes-Farley]

The only possibility, and its a slim one, is that low alkalinity limits coralline and coral growth, so more nutrients can go to algae.

[JudyK]

My calcium level had also dropped to 300. My coraline stopped growing and actually started coming off the back of the tank when the green algae started. My bubble coral started to decline then the algae overtook it and I lost most of my snails. I think this happened because of a bad bucket of salt. I've been doing frequent water changes and trying to bump up both calcium and alk. The calcium is now at 400 but the alk still wants to fall or stay low. I'm using baking soda for it. My PH is 8.4. I have phosban in the sump and run charcoal 24/7. Do you think if I can get the alk up it might help in this battle. I also have halimedia in the tank that is covered with the algae. If I can keep the calcium up, my hope is it would start growing again and out compete it.

[Randy Holmes-Farley]

Low calcium and alkalinity can stress or kill coralline and hard corals, so that is not surprising.

Raising the alkalinity will certainly help the coralline and hard corals.

[Glove]

Randy, can you verify if and how higher alk helps battle an algae problem?

?something to do with precipitating the phosphate?

[Randy Holmes-Farley]

I think the most likely possibility is that it allows corals and coralline algae to grow, using nutrients that green algae might otherwise get. Raising alkalinity is rarely an effective solution to algae problems,however.