Causes of decreasing kH???

[moppy]

Can anyone tell me what actually causes kH to decrease?

June 16th my kH was 10.0

June 21st my kH was 6.0

That's a rather large decrease in 5 days in my opinion? Maybe it's not?

Test kits have been verified as good by JL.

So, what are the causes of decreasing kH?

[gregzz4]

I chalk up my falling KH to coralline growth on my new LR

[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/2002/11/chemistry#section-1

[moppy]

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