Causes of decreasing kH???

[Snaz]

- Adding too much Calcium supplement
- Excess CO2 in the air
- Critters using Ca for growth
- Excess nutrients
- Overdosing alkalinity RELATIVE to calcium

If you haven't already read this article and then read it again and once more for good measure. I suspect your problem is "Zone 3".
http://www.advancedaquarist.com/2002...stry#section-1

[moppy]

What about overstocking of fish?
Does that cause a decrease?