01-19-2008, 08:03 AM
Join Date: Apr 2005
Location: Sacramento, CA, USA
iTrader Positive Rating: 100%
| | Re: What Causes My PH To Rise?
Assuming your KH is 18 ppm and not 18 dKH from the tap, your tap water contains some CO2, but not much in the tank water, so the pH goes up. That is low KH, so it doesn't take much difference in CO2 to change the pH that much. This is just a guess. DIY CO2 can lead to very little in the tank water if you have any leaks at all in the CO2 system.