i'm not sure you have a leak,about a year ago i wrote the same question.HOW MUCH WATER DOES THE AVERAGE POND DROP IN A DAY? i had a lot of people including bob lusk write back and say it's very normal for a pond to drop 1" per day.on a hot day wind wind blowing that's very normal,i know.not sure about your weather conditions now,but i would think these are ok levels.my 4 1/2 acre pond drops about 1/4" a day now.