I still maintain that you guys aren't completely getting them clean by just cleaning the outside surface, and there are issues effecting their performance in ponds that you're not seeing that I see in tanks.
Thanks Bocomo and Esshup for the strap wrench suggestion. I'll have to see if I can find one large enough.
I'm up to the challenge of building a gizmo.
Hey Phil when you're ready to pitch one just send it to me! :-)