Hello, this is my first post in these forums, lately I have encountered some problems with my KH in my medium to heavily planted 190l tank. I have a pressurized co2 system with ph controller set to 6.5.

Now normally I dont usually test my water, I do regular water changes of 25% every week. As of lately, I noticed that plants didnt pearl as they did before. After some water testing I found out that my kh is only 1 to 1.5, this leads to a low co2 count.

I have tested the tap water which I use to do my water changes, and the kh is 4.

How can I stabilise the kh of my tank so that I can have a larger amount of dissolved co2 in my tank.