Need some clarification on my CO2 dosing rate!!!! Urgent!!!

[PeterGwee]

Hi guys, need some help to clarify some of my doubts over pH/KH and CO2 level.

First, before i dose CO2 into my tank, the KH was 3. Therefore i aim for pH of 6.8 which will give me a CO2 level of around 14ppm. Now what i need to ask is do i need to measure my KH again to confirm that it is 14ppm? The doubt came as i measure the KH and to my surprise the KH went up to 5!!! which means my CO2 level is 25ppm(over the optimal range and properly dangerous to my fishes!!!) Please help!!! Thanks alot guys[]

[juggler]

kH rising due to CO2 injection could be caused by presence of coral chips in your substrate. As CO2 gets pumped in, the water becomes more acidic. This causes the coral chips to dissolve and so the kH rise.

Actually 25ppm is still OK for your fish. If they don't go to the surface gasping for air, then it is safe.

There's more in-depth discussion at this article: http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm