I've never seen shells in Flourite. Dark and light bits, yes.Your sure
it's shells? Did you have gravel or anything else in there before?

Ken wrote:

The subject pretty much says it all. I've noticed broken shells in my
Flourite, which I didn't put in there, could that be the culprit? I
can see that raising it a bit, but by 6 degrees? Is Flourite even
supposed to have shells in it? In case it matters that much I have 2
inches of Flourite in a 20 gallon tank. Any help you can give would
be much appreciated.

Ken

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Sherry Michael Weller
SAS Distributed Desktop Support
www.psych.upenn.edu/~sherrym