I had a few hundred thousand of them which I have dwindled to a few tens of thousands with an assortment of hermits. I tried everything else and nothing worked. Wish there was a better answer, but there isn't. I spoke to Dr. Ron Shimek who recommended for an infestation such as mine, taking out all the rock and killing everything may be the only way to rid my system.
They do seem to go up and down in their population though, but when your flow becomes hindered because of the thousands growing in your pipes, you may do like I did and tear the system down.
__________________
Hop
|