This has been creeping in very slowly and just bam got a lot worse today. I’m sure it’s GHA but it’s only on my frag plugs like the one in the picture. What’s the best way to go about removing it before it spreads more? I also don’t have a phosphate or nitrate number because I ran out of test about a week ago.
I run carbon and GFO.

I run carbon and GFO.


