KH and CO2

[cbster]

I am just starting to use a ro/di system and the water that comes out after I add Kent ro right has a kh of 2-3 degrees is that enough to hold the ph with a pressurized co2 system or do I have to raise the kh somehow and if I do how do I go about raising the kh?

 

[happychem]

Why RO water? First off...

What's the pH of your water after sitting out for a few hours in a shallow bowl?

I think that 3 degrees is the generally cited minimum, but the bottom line is that you'll have a constant pH as long as you have a constant CO2 input.

 

[cbster]

I am using RO/DI water because of the discus my water is real hard so I want to soften it up. I don't really remember what my tap water ph is after it sits for awhile but I think it was around 7.8 or so and with co2 added it is 6.8 the kh and gh is around 10 and after it is 2-3 and the discus seem alot happier.

 

[happychem]

I know squat about discus, but apparently they like really soft water. By soft I mean low total dissolved solids. If this is the case, there's really nothing you can do about increasing KH.

 

[djlen]

Discus can adapt to 7.8 fairly easily. Most breeders buffer their water down to the mid-6's to condition them, but they will adapt to a higher pH and should do well. They do require 82 - 84° water to lessen stress and maintain health, but pH is not as critical as some people believe.
If your tap water is hard, the odds are the kH is probably OK for CO2 injection which will bring the pH down.
I suggest you test your kH and pH out of the tap as happychem recommends and let us know what those values are. Using RO water might be unnecessary.
My water is 7.5 out of the tap and I can keep it at 6.4 steadily, with no variance using CO2(pressurized) indefinitely.

Len