Strange(or not so strange) snails

[Aude]

Hello, all. Haven't been around in a while, but hoping you are still as helpful as ever.

Yesterday the water level on my 12 g was looking a bit low so I topped it off with some dechlorinated water.Today, I awoke to find a bunch of snails, trumpets and the regular variety, floating on the top of the water. They are not dead...just floating. I know it's normal for snails to float on occasion...but does the number of floating snails signify something else, maybe about the water condition?

My last water change was last week, I do them every monday, around 1/4 water changes, and all levels check out normal as of today.

[smaug]

Thats happened to me once or twice,they were all smallish trumpet snails about an eighth inch long.There were no other problems with my tank at the time so I assume its ok.