Thanks for the information.

I am new to ponds and I was not sure if I had a leak in the pond or it
was evaporation. My 120 sqft pond is in three pools. There are two
sluices from the top to the middle and one from the middle to lower.
Sluice is about 9 inches wide. The upper ones has about 1 inch of water
flow through the sluices from the top pond and the middle has about 2
inches of water. I am loosing about 20 gallons per day so from what you
say I may not have a serious leak.

Jim and Phyllis Hurley wrote:
Our pond can lose an inch in a day, but we have two falls and two streams to
promote evaporation. It loses more like 1/4 to 1/2" per day if the pump is
off. Both surface and circulation count.

Jim