Scales coming off sounds like a parisites.. fulkes etc. Are the fish flashing? Draining your water is a good start but if parasites are present it will not remove them. Salt is a good start it treats a wide variety of problems at once. Like tad said throwing random chemicals is not a smart move.
Pine cone tad? You thinking he has dropsy if so the fish would be swollen up as well as a scale problem.
With all the leaves in his pond sounds like nitrites or nitrates are out of balance a simply water test would show that
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