On Sat, 5 Jun 2004 14:37:07 +0000 (UTC), Andrew Burgess
wrote:

I put a small pond in my front yard. It has some very small gold fish
that were not gold when I bought them, but are now turing gold. In any
case, the pond is a 60 gallon pond and each day that I turn the
fountain off, I wake up to find the water down by four to five inches.
So I drained the pond and checked for cracks and found none. It still
went down over each night, it was becoming a problem to put water in
it each morning. Then I left the filter/fountain on at night, I was
turning it off. With the fountain on, the water level is fine in the
morning, now two mornings in a row.

Is there a leak in the suction line of the pump? It would pull in air
when the pump ran but leak water when the pump was off.

Another possibility is a critter climbing to catch fish. You said
that you had some fish chewed up - was that after a night of no
fountain running?

If so, then the fountain may be warding off the critter. When the
fountain is off the critter climbs in and the displaced water spills
out. Then the critter climbs out carrying water in its fur or on its
skin.

A possibility.