Brown Slime - Possible Blue-Green "Algae"

[sacrifice333]

I'm a bit of a newbie to this crazy addiction we call reef-keeping. Anyways, I purchased a complete, running system in the late fall and have unfortunately had some problems with a greenish brown slime that likes to cover my sandbed and live rock. I think it may be some blue green algae.

For some background my tank is a 50 galllon bowfront. I purchased the system in November, prior to that it was running for over 2 years at the previous owners residence. It has about 40lbs of live rock, a couple inches of sand, a not so hot air-stone style skimmer, a 304 running charcoal and chemipure, and a 10000K 175 watt MH presently on for 7hrs per day. The livestock includes 4 small fish, one decorator crab, one cleaner shrimp, one coral banded shrimp, one sebae anenome, and several hermit crabs. I presently only have a few mushrooms, but will hopefully be able to add more as I rectify this problem.

So far in trying to clean up my tank and improve the conditions I have done a few things. I have gradually increased the salinity to around 1.24, it was sitting at 1.20 before. I have also starting dosing with Kalkwasser to help increase the pH level and prepare the tank for more future corals. I have been trying to increase the flow in the tank as well. I will probably upgrade my skimmer but have not yet done so.

Any suggestions to help me eliminate my brown slime - possible blue-green "algae" problem would be appreciated.

Nathan

[Delphinus]

Well, I'd say you've nailed the diagnosis, sounds like a classic case of cyanobacteria. Despite the name it can be just about any colour as well as blue/green (most often red, thus it's other nickname "red slime").

There's a couple of things to consider here. Basically, it will take off and do really well in a tank if there are certain conditions met. Most often, a buildup of excessive nutrients (nitrates and phosphates), also low O2 saturation, low flow, low or no skimming, old lamps or lamps with poor spectral output.

Upgrading your skimmer will help, no question. Also will increasing flow, and trying to manage your feedings to prevent an excess of uneaten food contributing to the buildup of nitrates.

You can also add a refugium where you can grow macroalgaes such as caulerpa, these will compete with the nuisance algaes in the main tank for the excess nutrients. It might not solve the problem outright but it can certainly help you out in dealing with it.

[monza]

How offen are you doing water changes and with what water - RO/DI is best. Also make sure you are not over feeding that could cause the excess nutrients as Delphinis mentioned. When you upgrade your skimmer do your reaseach and spent the money on a good one, your future corals will appreciate it.

Dave

[sacrifice333]

Thanks for the tips so far.

Two things I didn't mention were that a) I bought a new bulb in November, so the spectrum should be decent and b) water changes that I do are approximately 10% once per week (which sometimes ends up being 15-20% every two weeks) with RO/DI water.

For a skimmer I'm considering a Remora hang on type.

As for a refugiam, I don't know much, if anything about them... but I'll do some research.