Empirical method for finding leaks

Just came across your post on determining a leak in a pond and I have a question. I have a pond that is approximately 2400 gallon that is filtered by a bog. I am losing about 100 gals. of water daily. We just replaced the bog liner to be sure it wasn't the culprit, but it's June, in the south, and I can't turn off all my filtration for several days. I also have a small underwater filter/fountain I run when it gets in the 90's. My bog has a 3' spillway that aerates my pond. Can I still use the milk jug test for a leak? The pond is in sunlight about 2/3 of the day. Thanks for any help you can give