Question about PH/KH and CO2

[Lampshade]

I noticed a couple of my fish this morning gasping for air. I immediately pointed powerheads at the surface and ran some tests while I got a water change ready. When I ran the tests in the beginning I showed a KH of 16dkh. This seemed VERY high seeing how my calcium was normal at 420ppm. My KH/Calcium have always been pretty balanced, and I run a calcium reactor and dose kalk, so they stay fairly balanced.

Anyways, I started to wonder about possibly a bad test, so i re-did the test. MY KH was back at 9-10dkh, right where i like it. This seems better, but it's such a simple test I don't think i could possibly screw up counting drops from one bottle. I also noticed EVERYTHING in my tank doing much much better, coral polyps where back out, fish where no longer stressed and gasping. So I assume I had very low oxygen in my tank.

I"m thinking that my very high CO2 levels would give me a false high KH level? My PH went up about 0.2 during this from 7.9 to 8.1 over an hour.

I know with planted tanks there's a close relationship with KH/CO2 and PH. I was wondering someone knows if the same goes for salt water?