"dt" wrote in message
...
snip
Just curious; with a bottom drain into the lower VF, what happens if the
power or the pump goes out?

I lose circulation, and potentially my main pond would overflow about 1/2-1
inch of water as the bigger VF area drains down into the lower. I used to
have a check valve in place at the in-flow of the VF, but I recently took it
out.

BV.