• Journal of Bio-Environment Control
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• v.11 no.4
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• pp.188-192
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• 2002

High concentrations of HCO$_3$$^{[-10]}$ (bicarbonate ion) in hydroponic water lead to high pH and to change in solubility, and consequently inhibition of absorption of available iou. An adequate and practical method is needed to remove HCO$_3$$^{[-10]}$ in the water fur hydroponics. to compare the efficiency of HCO$_3$$^{[-10]}$ removal, the effect of injecting HNO$_3$, H$_3$PO$_4$ or H$_2$SO$_4$ was tested. Acid injection was effective to remove HCO$_3$$^{[-10]}$ Based on the assumption that an equivalent of HCO$_3$$^{[-10]}$ ion is neutralized by an equivalent of acid, KHCO$_3$ was dissolved in a double distilled water at 50, 100, 150, 200 or 250 mg.L$^{[-10]}$ concentration and either HNO$_3$, H$_3$PO$_4$ or H$_2$SO$_4$ was injected at a certain ratio, and the resulting pH change and HCO$_3$$^{[-10]}$ ion removal was measured. According to the results obtained, HCO$_3$$^{[-10]}$ in hydroponic water was titrated, and concentration of the residual HCO$_3$$^{[-10]}$ ion well correlated with the amount of acid injected.