Hammer in Trouble (I think)

[first-chevalier]

Tank parameters:
10g Display, 5g fuge, salinity 1.021, temp 76, lighting is 2x26w 6500k plus 2x20x Corallife 50/50 (all four CF). Amonia-0, Nitrite-0, Nitrate-20ppm (just saw this but don't know if it's important or what to do about it if anything), PH 8.0. No new additions but had to replace my mag3 with a quietone1200 within two weeks about the time this started (but I think this is coincidental). It's also just started getting cold in the tank area too and had to turn the heater on recently.

The Issue
I've got a hammer that's been doing quite well and went from a two head to a five head since about April. However, recently my mag3 went bad and I had to replace it with a quietone 1200. I think that's purely coincidental though. I noticed a yellow sponge growing under the hammer heads so I asked my LFS who have been VERY helpful to this point. Yes, I know LFS's have a rep but I asked them anyway. Now, however, things are getting worse and before I pull the hammer out and scrape the sponge off I wanted to ask you guys what you think. Here's a pic if it'll help. Thanks in advance.

http://reefcentral.com/gallery/data/4531/144719Hamer-sponge-web-med.jpg

 

[m2434]

I would be skeptical that the sponge was the problem. My Hammers have some big blue tube sponges growing all around them and their perfectly happy. They do like moderate flow, so if you changed the pump, maybe something changed there. Also they seem to like reasonably strong lighting...

 

[Lotus99]

Your salinity seems low for corals. Most people keep their salinity at around 1.025.

 

[fierceseaman]

I would have to say the salinity is low as well. Try bumping that up to 1.025 and I bet they will love it.

 

[first-chevalier]

Okay, I'll try increasing the salinity. Today they seem to have snapped back and look just like the other head all full and healthy. The temp seemed a little low to me so I bumped it to 78 last night as we had our outside temperature drop into the mid thirties. Now they seem quite happy. I'm wondering if it's both a case of lower flow and lower temperature?

 

[first-chevalier]

Oh, I've kept my salinity at 1.021 since Feb, when the tank started. the hammer has gone from two heads to five now. Does a higher salinity mean it might grow faster then?

 

[first-chevalier]

Well, the hammer seems to be doing okay. The two heads have flushed-up and look as well as the other three on the opposite branch. I'm guessing they're not as full as they used to be due to the flow issue, but I plan on ordering my mag three next week so that should go away eventualy too, I hope. The coloration etc just alarmed me when I got home that one day. Thanks for your help and input guys. OH, and I'll be gradualy increasing my salinity over the next month as well.