"alex crouvier" wrote in message
...
If you have sof****er (gH, kH 3) and employ DIY CO2 at 15ppm,
what do yo do to increase gH and kH? pH is at 6.8


Nice pure water. Is the question regarding an existing tank with CO2 or
adding CO2 to a tank with that water?

It is my understanding that you need to maintain a kH of 3-4 to prevent a pH
crash when adding CO2

If you have CO2 I assume you have a planted tank, I've seen a gH of 3
recommended as a minimum for planted tanks.

What kind of fish? That's pretty soft water, fine for some bad for other
fish. Baking soda will raise both the kH and pH.

Bob