Hmm. I have some elongated xenia that wasn't pulsing at the store where I purchased it (imagine that, purchasing xenia) and has never pulsed, but will grab bits of food at feeding time. I have some silver xenia from Tim's that was pulsing wildly at his store and only pulses occasionally at my house. And I have some pom pom xenia that pulses like it's going out of style. The only thing I can tell is the flow is different for the 3 guys. The elongated is in a relatively high flow area and gets blown all around, the silver is below that on the sand bed and gets bent over backwards a bit now and then, and the pom pom is in front of those next to the ricordeas and seems to be in a lower flow area. The elongated grows like a weed; when I got it it was a 1" tall stalk on a rock, now it's a 10" tall tree with a few dozen branches, so I guess it likes something.