UPDATE - QUESTION as to NEW ISSUE
Since using the medications, the Koi seem to be doing much better. They are more active and there is little to no bunching up under the waterfall. Thank you to all who provided advice.
BUT - the goldfish are turning white and dying. I had hoped it was natural color change but it is obvious that it is not. The goldfish start to turn white; are more lethargic; and die. They appear as if all the blood has been sucked out of them.
I've lost 6 various sizes of goldfish within the last week. The photo here is from this morning.
This morning's testing showed - 0 of ammonia; nitrite - but a bit high on PH 8 - 8.5 depending how you read the color. The water temp is 64.7 F.
There has been foam on the water off and on for the last couple of weeks - yesterday more so. I assumed they were spawning which might be the reason for the higher PH.
I added more baking soda to the water today with the high PH #'s.
I just don't know what more to do. My filter system is excellent - I haven't put anything new in the pond - no new fish - has no rocks - I feed them Dainachi medium and small pellet food.