PH control in flood/drain hydroton
my method of preventing too high pH levels in the hydroton medium. First, check if the irrigation water pH is set at the correct level by checking the pH setting, and monitor
the quantities of acids actually being added to the mixing tank.
Not ideal if you have even small amounts of bicarbonates in your raw water
My method is to control the pH by increasing the ammonium level. This is done by swapping calcium nitrate for ammonium nitrate
increased amounts of ammonium to a nutrient solution when the pH in the root zone is rising,
which usually occurs as a result of high vegetative crop growth rates.
The roots will take up the NH4+ions and
release acidifying protons (H+) into the root zone. This acidification of the root zone will create a beneficial environment for the uptake of nutrients by the plant.
In hydroponic growing systems, the proportion of ammonium cations should be limited to 5-15% of the
total nitrogen in the solution. A maximum of 1-1.5 mmol/l (14-21 ppm N) NH4+ in the nutrient solution is
acceptable; if higher, the pH will drop too much. The exact quantity, however, can vary from 0-1.5 mmol/l
(0-21 ppm N) depending on the actual growing conditions and the sensitivity of the crop to a low pH.
When the pH is too low, reduce the ammonium input to 0-0.5 mmol/l (0 - 7 ppm N). When the pH is too
high, increase NH4+
to a maximum of 1.5 mmol/l (21 ppm N). The pH should be checked daily.
Once you know your crop well,keeping records you will know the ballance of calcium nitrate to ammonium nitrate, especially using rain water or RO water.A