Re: Biogenic decalcification
If your pH rises during the day and falls at night, then the rate of
uptake of CO2 into the plant is greater than the influx of CO2 into the
tank. This creates a CO2 deficit during the day. Biogenic decalcification
will ONLY occur if your plants are able to 'use' bicarbonate. In the
course of bicarbonate uptake, hydroxyl ions are released by the plant ...
these ions react to form calcium carbonate which then precipitates out of
sulution, hence the decalcification. Depending on your CO2 deficit, the
pH could rise as high as 9 or even higher ( only if your plants use
bicarbonate ... in fact this is how early experimenters determined which
plants could use bicarbonate). If your plants cant use bicarbonate the pH
will still rise but not as high and the Ps rate of these plants will be
significantly reduced when the pH does rise.
The solution is to increase the influx of
CO2 into your tank. In a recent rant I recommended increasing the flow
rate of water across the top of the tank, either by powerheads or
aeration. Alternatively, you could add ... dare I say it ... CO2.