If you removed the cartridge within a day or two after adding your stabilizer, if the stabilizer was added via the skimmer, then you've probably removed it with the cartridge.

Along with the info watermom requested, also please tell us whether you added liquid or granules for CYA, and did you broadcast it, hang it in the sock, or put it in the skimmer? HOw long did you wait after the CYA addition to test for it?

Janet