06-30-2009, 11:44 AM
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Originally Posted by abunari
so the tannins of the driftwood are what affects the ph slightly? if my water is already have a high kh if I let the water sit for a period will the buffers dissipate out to where the driftwood wiil help lower the ph?
It will be very slight. Another member (can't remember who at the moment) in a different thread recently mentioned a lowering of .2 with a lot of wood in his aquarium. I have a lot of wood in my aquaria, and I have very soft water out of the tap (pH is 6.8) and my tanks run at 6.2 to 6.5 with the diurnal variation. I suspect it is the normal biological actions and nitrogen cycle in the tanks more than the wood, although the wood may add a bit.
I have about half a cup of dolomite gravel in a nylon bag in the top chamber of each filter to maintain a pH above 6 (without it the pH drops). The dolomite adds some GH (General hardness) and KH (carbonate hardness) to my water that is very soft, and it is the KH that is the buffering agent for pH. I personally don't know how long water in an aquarium will retain its inherent bufferent capacity, although I have read that continually adding acids will at some point cause the buffering capacity to be used up and at that point further acid would significantly drop the pH (to the fishes detriment), something to be avoided. I would suspect that the acid leeching from wood (through tannins) would not be sufficient to significantly alter your water's buffering capacity if it is hard to begin with. And the weekly partial water change would counter this effect before it became serious, in my view.