The more water that is in "reserve" means that during periods of quick temp changes, the water will change temp more slowly, creating less stress for the fish.

Regarding your well. Do you know how many GPM it's output is? Do you know that the well will keep the pond full?

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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).