Planted Tank Obsessed
Join Date: Dec 2006
Location: Saylorsburg, PA
What about simply mixing in a small amount of tap water? If that's out of the question, and you feel you have to add something, wkndracer's suggestion is good. Some plants though, do not like Sodium in my experience.
Although I don't feel the need to add any buffers to my RO, the more I think about it if I were to add something for kh, I would add potassium bicarbonate. Seachem Aquavitro has a KH product that seems good called carbonate™.