On Tue, 20 Jan 2004 09:24:12 -0500, "Nemo" wrote:

My kH is very low, about 3 dKh causing pH swings. I want to minimise raising
the pH. What is the minimum kH needed to maintain a reasonably stable pH?

A KH of 3 will not cause pH swings.

As long as there is SOME buffering (KH of 1 or more), then the KH is
NOT the cause of any pH swing. A low KH will result in a lower
overall pH value, but it won't change the pH swing.

If you are getting a pH swing, then some change in the acid level in
the tank is occuring.

In a non-CO2 injected planted tank, you will often see the pH rise
during the day, as plants strip out all CO2 from the water, making the
water less acidic. Then at night, CO2 levels return to the ambient
3-4ppm.

Since the KH isn't the cause of your pH swing, give more details about
your tank setup, and exactly what you are seeing with your pH
readings.


Chuck Gadd
http://www.csd.net/~cgadd/aqua