Thanks to all of you for sharing your valuable insight. I feel more confident
than ever.

BTW, my pond is 2200 gallons, not 220 as I mistyped. In fact, it is 2200 gal
plus a 50' long stream which includes 5 smaller pools. When I build the system
I over designed the filtration in anticipation of my koi growing (I have 9 that
range from 4" to 12"). I also have UV, a skimmer, bottom drain, and lots of
plants. I test my water every other week and it is always near perfect except
for salt levels that change with my bi-weekly partial water changes. The water
is always crystal clear.

I'm on day 2 of my PP treatment. Fingers still crossed!

Thanks again, group,
Gary