cocoon, crud and algae

[hkalmus]

I've got this large white fibrous mass that looks like a cocoon growing in a crevice of my live rock. It's a bit smaller than a golf ball and changes shape from time to time. Does anyone have any idea what this might be and will anything horrible come crawling out of it. I first noticed it about 6 months ago but it may have been there longer (I did some rock rearrangement, moving rock from my smaller tank to the current tank).

Second question: My tank is about 9 months old. I cycled about 50 lbs of live rock at the start and have noticed recently that there is a lot of crud on the rock, looking like decayed plant matter or just plain dirt. Should I leave it alone? I was thinking maybe I should brush a little bit off every day and hope the skimmer picks it up. Water quality is fine and all residents seem quite happy.

Third question. I've got a case of the dreaded red slime algae which comes and goes to varying degrees on a daily basis. Are there any critters voracious enough to handle this problem, should I brush it away as much as possible (and will it foul the water)? Any other suggestions. Thanks Harold

 

[mogurnda]

1. I'd vote sponge. There are many species that do relatively well in reef tanks. Or maybe a tunicate. In any case, it is a good thing if it is growing well. Unless something nasty crawls in, nothing bad will come out.

2. Detritus, the stuff settling on your rock, is generally a source for nutrients that will feed algae (like the cyano in question 3). The best thing to do is siphon it off the rocks, or blow it off with a powerhead/turkey baster and let the skimmer deal with it. Every few water changes, I use a hagen 402 powerhead and become "tropical storm dave" to get the gunk off the rocks and out of the nooks and crannies. Sometimes I just let the skimmer deal with it, sometimes I use a mechanical filter, like a quikfilter on the powerhead, for a few hours.
Most of my stuff is snail poo, I think.

3. The best things to reduce cyano outbreaks are:
-increased circulation, trying to avoid dead spots in the tank
-reduced nutrients (you didn't mention your nitrate and phosphate levels)
-increased calcium and alkalinity, to give an advantage to coralline algae
There are some animals that eat it. Scarlet hermits nibble at it, and there are a few species of sea hare that prefer it, but the best method for me has been prevention.