Pyramid Snails

[b.branscombe]

I introduced five zoa colonies into my tank one week ago, and some of them started having troubles. Two on the left side of the tank started declining, with the polyps no longer extending and the outside tissue going from a purpleish colour to a faint white.

I did a freshwater iodine dip using Seachem Reef Dip (could not find Lugol's at any of the local pet stores, is there anywhere else to buy it?).

Soon after placing the colonies in the dip, I noticed a large pyramid snail near the top and removed it. Is it possible for one snail to eat 10-15 polyps in various areas over the course of a week?

Another thing I was thinking originally was that the 250w MH lighting was too much for them, so I turned off the halides directly above them, lighting them only directly with 96w actinics. They didn't seem to either improve or get worse, and this was about five days ago. Should I turn the MHs back on?

 

[b.branscombe]

Sorry, turns out what I found was a sundial snail, not a pyramid.

 

[zolovinglover]

Even a sundial can't really eat 10-15 polyps a night, but try looking harder, I would not be surprised if you find a few more sundials.

 

[b.branscombe]

These didn't just disappear in one night. I've estimated that I've lost that many over the course of a week. I found some Lugol's at a local pharmacy and dipped all the remaining colonies tonight using the directions at the top of the page. Fingers crossed. I noticed that in the colonies there are a lot of what look like mussles in between the branch like rock. I assume they're not predatory, but could they be aggrivating them?