Buffering? What buffering?

Watcher74, FWIW I had a similar issue with my water. I had a high pH and low KH of about 40mg/l which is somewhere in the 2-3degree area. I was worried about pH crashes but really couldn't do much about it because my pH was near 8.

I added some driftwood which I was worried would crasht the pH due to the acidic tannins in the wood. It did lower the pH but there was no crash. Based on this little experience I would have to say that you will probably be okay with regular tank maintanence and no C02 injection.

My final decision was not to mess with the KH until it proved to be a problem.

Tom
 
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Of course those CO2-KH-pH relationships assume that the only buffer present is carbonate-bicarbonate. It's not a bad assumption, especially if you have good maintenance, read little or no PO4.

Driftwood/tannins (like from peat) won't raise KH since they produce H+ at the same time as releasing the buffer of interest. Specifically:
KH = buffers - (H+)

So adding CO2, which produces carbonate/bicarbonate when it equilibrates, along with an equivalent amount of H+, lowers pH, but has no effect on KH.

I would suggest that unless you're embarking on the CO2 injection path, you needn't concern yourself with increasing your buffer. There's no easy way to do so without also changing pH. As long as you're reasonably diligent with water changes, you shouldn't have any problems.
 
Pretty much agree w/happychem, but even in an unplanted tank, KH is burned by normal operation as nitrification uses up KH (is an acid-producing process), so happychem's statement "As long as you're reasonably diligent with water changes, you shouldn't have any problems." needs to be highlighted. If your source water is low KH, you must be diligent about water changes and/or stocking and feeding levels or you will pH crash (due to buffer depletion).
 
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