Erythromycin and Corals

[Aquadan88]

Hey. Got a question. I went away for a week and my dad ended up heavily feeding my tank. Started to get some slime algae in my tank. Dosed with erythromycin last night, and I've noticed that my polyps are not looking too happy.

I probably should have checked this before I dosed the tank, but is erythromycin harmful to corals and polyps? I did a quick Google search and couldn't find anything.

 

[Sean Irwin]

It's unlikely to be toxic to the corals but may negatively impact their algae symbionts. You've also done collateral damage to the normal and necessary bacteria communities that control denitrification and other processes. You've also liberated huge amounts of previously locked nutrients released from decaying microorganisms, which is going to fuel another outbreak of nuisance algae. Remember, there are no quick fixes in this hobby.

 

[Aquadan88]

I do realize that, however, I've always found that the best way to get rid of cyano is remove as much manually, and dose lightly with EM.

I don't normally use the recommended dosing instructions. I use the "directed" directions for the first dose, but I don't put any more in. In this case, 400mg of EM, and then I will wait a few days to remove with carbon.

 

[joefitz]

I haven't experienced any noticeable, bad side effects from dosing erythromycin. I've done it twice now and both times it has cleared up the slime algae problem without seeming to bother much else in my tank...corals, fish, inverts...no impact from what I can tell.

I'm sure it does impact the bacterial population quite a bit as well; I'm guessing there is a cycle occurring after treatment...but it hasn't seemed to impact anything in my system in a noticeable fashion.

And in hopes of not starting a flame war, I am not suggesting erythromycin should be everyone's first effort at solving their cyano problems. By all means, try to figure out the cause and address that in every way you can. If you believe it is a nutrient problem, feed less, skim more, do water changes... If you think it is poor flow, add/redirect pumps. But when all else fails, erythromycin has been INCREDIBLY effective for my 500g system the few times I've used it over the past several years.

 

[Aquadan88]

K. We've been using erythromycin for years in the maintenance business, and using it in combination along with addressing the underlying problems seems to have a great effect on the cyano.