gizmo wrote:

"if GH and KH are each at 2-3 or greater" Can you please elaborate on this
?
Do you mean the delta between GH and KH or their degree (which is soft....)
10x

If GH is lower than 2, you may not have enough calcium and magnesium in your tap
water to sustain plant growth. You may have to supplement.

If KH is lower than 1, then as biological processes use up the small amount of
carbonate, your pH can drop too low.

I was not describing the delta between GH and KH.