It is possible that you are having water run under the liner lifting the
liner during heavy rains, and then as the water is able to percolate down
into the ground, the liner subsides back to its original location, leaving
the pond level lower than before the rain. If the water level is higher
than the surrounding ground level, the weight of the water in the pond will
hold the liner down, preventing the water from building up under the liner.
If you are experiencing this, then a trench around the pond to divert the
runoff would be beneficial.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html
"Pam Gibbs" gpaktatnetdoordotcom wrote in message
...
Today we had a couple of hours of heavy rainfall, and when it stopped
raining the water level in my pond had dropped four inches.

I know that water moves through the kiddy pool part of the filter very
slowly, and that it stays so full that lots of rain will cause it to
overflow. My question is, when the kiddy pool overflows does it just
spill
out the excess rain water or dies it also spill pond water too, and thus
cause the drop in the pond level?

I'm not even sure that question makes sense... Sorry,