2 part question

[jarrette]

1. I got this rock a couple months ago as a bargain basement $10 buy @ aquarium designs and the little corals have spread, but they seem like they hardly ever open up. Is there a reason for this? The insides have a really nice bright green coloring, is there an official name for these guys?

2. Also notice how much hair algae (is that the right name?) and macro has grown on the rock in 2 month in my tank. Is this a problem for a cleaner crew to solve? Is there a deeper issue with water quality that is causing the growth? Is the growth neccesarily a bad thing?

http://www.boondel.com/images/aquarium/colony.png

[hobogato]

your phosphates are probably a little high - hence the hair algae growth.

[jarrette]

whats the best way of getting the phosphate level down?

[hobogato]

a phosphate remover like phosban in a small reactor.

[Ed]

1. They look like green zooanthids to me.

2. Yes, a cleanup crew would help. Water quality could be contributing to the problem. Have you tested it? The hair algae can/will choke out other (desirable) things if left unchecked.

HTH.

[RayAllen]

I had green hair algae like that on some of the rocks in my 210g. Once introduced my foxface ate 99% of it in a 24hr period. Not sure what size aquarium you have though so hermits would be a good alternative.

[MissT]

I'd take the rock out with some used tank water in a 5 gallon bucket next time you do a water change. Pull off as much of the algae as you can, and on the spots there's no coral, use a toothbrush. The algae can definately out compete the coral and kill it. Maybe list your tank specs and what clean up crew you already have if you want help determining whether you have enough/ what to add...