Been 'away' back at the farm and just tested the pond.
pH spot on at 7.0
Alkalinity I think is low at 21ppm.
Question - What is the "Desired" alkalinity ppm? I have powered gypsum to raise it and add calcium.
From - [url=https://wkrec.ca.uky.edu/files/alkhardness.pdf][/url]
Most aquatic organisms can live in a broad range of alkalinity concentrations. The desired total alkalinity level for most aquaculture species lies between 50-150 mg/L CaCO3 , but no less than 20 mg/L.