Originally Posted by Swampman
I use liquid CO2
,Excel. My plants look great. I never knew that Lime could come from plants.
Sounds like biogenic de calcification?
And I quote from Diana Walstad's book 'ecology of the planted aquarium'
'Some bicarbonate users polarize their leaves during bicarbonate uptake. Polarized bicarbonate uptake has been described for Potamogeton lucens. The plant excretes H= (acid) on the leaf's underside to generate a pH of about 6. The acidity converts bicarbonate to CO2
, which diffuses into the leaf to be used for photosynthesis. In order for the plant to maintain its internal charge balance, H= is taken up by the plant on the leaf surface resulting in a high, localized pH (about 10) and a high hydroxide (OH-) concentration.
The OH- combines with calcium bicarbonate [Ca
(HCO3)2] in the water causing the precipitation of calcium carbonate (CaCO3) on the top of the leaf. In hard, alkaline water, this reaction, which is called "biogenic decalcification," may be so great that crusts of precipitated CaCO3 may weigh more than the underlying plant. I have seen CaCO3 deposited as small white "pimples" on the leaves of Egeria densa and Ludwigia repens when they were grown in hardwater under intense light'
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