How to raise KH level only

[flyfisher110]

I do a water change every week 25%. The GH - KG - & GH level are usually OK. For the last 2 weeks the PH level is 7.5 good the GH level is 100 OK the KH level was 70 last week so I added ¼ tsp acid and ¼ tsp alkaline buffer, the KH level dropped to 60.How do I raise the KH without raising the PH.
I have guppies and neon tetra's.

 

[Delapool]

Honestly I wouldn’t worry too much for either of those. It’s pretty hard to raise kh only - looking back on notes.

 

[Delapool]

Hmmm, potassium carbonate maybe but never tried it / not sure on chemistry.

http://www.theaquariumwiki.com/wiki/KH