| | Re: 4Dkh from Ph4?
Many of may tanks have KH of around 4-5 degrees, and a pH ranging though the upper 6s and low 7s.
I do not think water with KH of 4 degrees could have a pH of 4. Not saying it is impossible, but I do not see that.
Even my tanks that show no KH have a pH of about 6.0