I have two small frog ponds in a partly shaded area. I've got a few resident green frogs and a bunch of baby frogs each year, and I seem to have a constant population of tadpoles including some that overwinter. Between the frogs and the leaves that fall into the ponds, I have four or five inches of muck built up in the bottom. The tadpoles love to hide in it, and every time I try to scoop out the muck I end up with tadpoles that I don't want to kill. I want to use a pond vacuum to clean out the muck but don't want to mangle or kill the tadpoles and other pond life. Are there any pond vacuums that are safe for the critters in the muck? If not, can anyone recommend a safe way to de-muck? Thanks!