jled- to find degrees, divide by 17.8 if I remember correctly
KH 40 = ~2
GH 140 = ~7-8
I like to keep my neos in 7+ph, but if your neos grew up in 6.8 I don't think that's the challenge. Other params are good.
Sounds like a challenge I had when I was first starting years ago. All readings were good, but I'd lose shrimp due to tap things that couldn't be measured. What's worse, it can change at any time. I'm almost willing to bet if you were to switch to remin RO, deaths would stop...
Does your tap have chloromine or chlorine?