Been crunching numbers since I saw your post. Over the last four days I have dropped 1 3/8". I am not sure about my evaporation rate. My pond is not exactly straight east of Lincoln, a bit south. I think I can assume it would be similar to your 1/4" evaporation rate per day. If so, I'm really not doing too bad. The total loss is .34" per day. That is 10.3" per month. Which is certainly a slower leak rate than before treatment. If we go through another four month time period without rain, I'll be better off than the last four month long draught.
I did only spot treat, so I cannot expect a 100% seal. My apologies, if I appeared too negative. I was pretty pumped when I only lost 1/4" that first day.
FYI, we are supposed to get some rain tomorrow. Then cooler weather. The good news is, my SMB are fat and happy.



Difference between .33" and .25" is .08" - I think this could very easily be due to evaporation - if not triple that number.

9 yr old pond, 1 ac, 15' deep.
RES, YP, GS, FHM (no longer), HBG (going away), SMB, and HSB (only one seen in 5 yrs) Restocked HSB (2020) Have seen one of these.
I think that's about all I should put in my little pond.
Otter attack in 2023