So I went on vacation and had paid someone (hes local in San Jose, California, he works on koi ponds, maintenance and all of that) to clean the pond, trimmings and take care of the fishes. He also sold me one of his kois in late June (i think he runs a koi rescue thing as he always have new fishes for sale on Craigslist) in which it was my mistake for not quarantining it in return for a discount on pond maintenance. Prior to that I bought three kois from Nextdaykoi in early June.
He admitted that he dosed my pond with Potassium Permangante before he left which I came home to my pond being purple because he felt that my pond needed to be dose with it weekly in small amounts as assurance (never heard this before). The kois looked fine until the next day. My pond is aerated via waterfall. Some of the kois started staying still in the corner just gasping. He said "Just prime it" and had me doing a 50% water change. Few days latert i did a 25% change and few days later i did another 25% as told to do so.
My pond is pretty established, not too overstocked. Good filtration.
Everytime i changed the water, i dosed with Prime. The temperature stayed around 85 degrees on average but the water was about 72 degrees on average during the day time.
Over the course of the week, i lost four 16"-21" kois and 9 smaller sizes between 5"-10".
Honestly i have been trying so hard to figure out what is wrong. I initially thought it was KPV just by how the kois had died (gills all brown on the exterior, red streaks on fins, eyes sunken in, signs of ick, etc...) but honestly it could be any of the other diseases as well...
My pond parameters at the moment:
Ammonia: .15
Nitrite: 0
Nitrate: ~30PPM
PH: 8.2
GH/KH: According to the strips (awaiting my amazon package for the liquid test by API), the water is around 180 hardness
My questions;
1) What the heck is going on? Did PP just destroyed my cycle and threw it off balance?
2) KPV possibly?
3) Why is my PH so high, this was tested during the evening at sundown
4) My ammopnia is high and i have been watching it and just dosing with Prime daily.
5) How do i prepare myself for Nitrite spike? I was reading about SALT, are there any guides for this?
6) I know i should be adding baking soda to reduce my hardness? Is there a guide to how much i should use as well?
7) My pond is about 5000 gallons, it currently is drained down to 2500 gallons so its easier to dose - does this matter? Should i put in more water?