Something is Seriously Wrong

[nano reefer]

Well over the last month or so i have had some problems in my 55 gallon tank. Parameters have been excellent, i test once a week with Salifert. I haven't changed anything since i started the tank. Okay, now the problems i have had:
About a month ago my beautiful rock of yellow polyps started losing their numbers, after about a week i went from 200 - 150 polyps. Then a little bit after that my green zoo rock just closed up and never opened again. My most prized acan rock, was dying around the edges of the rock, and when i started seeing 1-2 acans die per day, i fragged it hoping it would get better (not sure why i did that).Then a small orange/green zoo rock that had previously had troubles a couple months ago started losing polyp count. The rest of my yellow polyp rock died about 2 weeks ago. Then this past week my 400 polyp orange zoo rock lost about 100 polyps. Then today i just noticed my 6-line was missing, i had seen him last Friday, but not today.
Some good things that have happened are that my bubble coral survived after a month of extreme care. My colt coral is growing like a weed. I also just found 2 peppermints i bought about 3 months ago, that i never saw in my 55, and i figured they were dead.
In my 14 Nano, everything i fragged from my 55 is thriving: acans, yellow polyps, hammer coral, and various zoos. My 14 is doing great and the water is the same, so i am wondering what is going wrong.
I just freshwater dipped all my zoo rocks today for 20 minutes, it was about an hour ago so i havent seen any change yet.
Just a bunch of seemingly small things added up over a long period of time and i realized how much of a loss i took.
I was just want to know what i should do. Help me please.

 

[rcoultas]

Give a run down of the parameters and the inhabitants in the tank - that will be a place to start for someone to perhaps pinpoint your problem. Also type of lighting and how long these corals have been in the system. If you could post some pics that would help too.

 

[fish addict]

the first thing I think of would be a bristle worm, not the ok kind, like the coral eating kind. Just throwing that idea out there, you might want to watch the tank a bit after the lights go out to see if you can spot one.

 

[wattsupdoc]

I would suspect a predator. Could be several different things. Also, I wouldn't suggest doing a FW dip on any invert you want to survive. Corals are inverts. A iodine bath would have been more appropriate. Maybe I'm wrong about the FW dip, but someone will surely back it up or shoot it down. However, I wouldn,t do it. Nor have I ever heard of anyone doing it.

 

[nano reefer]

I already dipped them, i was hoping a nudibranch would fall off the zoos.
And 6-lines eat bristle worms? This problem has been goin on for a while and my 6-line has only died recently.
The corals have been in the tank for months.

 

[nano reefer]

if it is a bristle worm, how do i get rid of it?

 

[fish addict]

if it is a big one you just have to watch out for it while the lights are off and try to pick it off in one piece. I read some article where a guy with a huge tank like 600 gallons or something was having a problem with his soft corals just dissapearing overnight. after a while he caught like a three foot long bristle worm in the act of eating his xenia. That was the first thing I thought of especially since you seem to be having a problem with one thing then something different.