[htfn]

Originally Posted by Delphinus

http://www.reefcentral.com/forums/sh....php?t=1869000

Suggests in there another possibility is that there is calcium buildup inside the impeller or the shaft, impeding it's ability to shift upwards when spinning in the reverse direction. In that case a vinegar bath should fix you up..

Thanks for this info. I just read it, and I have to check again to see the housing for 4 tabs.