Fish loss or no fish loss, going from 5-6" daily to 1/4" inch daily is huge! Think of the cost of draining and re-packing if not re-coring and lining?
5-6" loss per day is not a pond, but a retention ditch. 1/4" per day is acceptable and makes a pond.
Heck, I am at 1/2" per day, and think the prospect of knocking that down to 1/4" or less would be great, and if the same ratio as you achieved evaporation would be greater than leakage!
I would guess the color changed as the ESS was giving the ecosystem a kick in the pants. Now that the ESS is lowering in quantity in the pond, the life is coming back. I would still set up an aquarium with pond water and drop in a fish or two to see when it is safe to re-stock. FHM are not a good indicator, they are tough and will live.
