Fishhead,

Even if your redears take off and reduce the snails they will not eliiminate them. That said the reduction of parasites greatly outweighs some cleaning the snails do. I personally don't think the snails contribute that heavily to the overal "clean up" of a pond anyway. Lots of other factors that are more involved in the "cleanup" of a pond and overall health of your pond.

I take it a step farther on my ponds. Not ony do I have snail eating fish (yellow perch in my case) I also elimiate the other link in the parasite cycle -- herons. I have put in nonlethal means to keep the herons away. After a couple years I don't see the parasites I used to see in my fish. In fact I don't see them at all.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.