AnselAdams
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I am going to kick this off by reposting something I posted in answer to another question on The Farm regarding the inability to maintain PH stability.
. . .
I too have been having an issue with maintaining a stable PH. I did some research into buffering (remembering my saltwater reef days) I hope this helps. The short version is that if you are using RO water, a gram of baking soda per 5 gal/20 liter will set your alkalinity to about 60-70 ppm. I used a hanna freshwater tester to figure it out.
Hanna Checker on Amazon
. . . "This one only applies to those of you who are using RO water and relates to
water alkalinity and its ability to buffer pH. For those of you who are using mains
water this material doesn’t apply due to mains water often possessing high
alkalinity (often far too high) values. Alkalinity is best expressed in this case (so
as not to confuse things) as the buffering capacity of water. That is, the
alkalinity of water is related to the pH, but it is actually a different parameter. It
is a measure of the capacity of the water to resist changes in pH. Don’t confuse
“Alkalinity” with “Alkaline” (which relates to an alkaline pH of above 7.0). The
higher the alkalinity, the more acid can be added without considerably changing
the pH. This is because the bicarbonates (HCO ) and carbonates (CO )
react with the hydrogen ions (H ) contributed by the acid, preventing them from
dropping the pH. Alkalinity is typically expressed as the equivalent concentration
of calcium carbonate (CaCO ). The ideal range for alkalinity as ppm CaCO is
expressed as 40-60 ppm, with 20-80 ppm being the outside range. Calcium
carbonate is 60% carbonate and 40% calcium at 100% purity. Thus to equate
60 ppm CaCO into how much carbonate this represents 60 (ppm) – 40%
(calcium) equals 60% Carbonate, so 60% of 60ppm = 36ppm carbonate. This
would equate to 1 gram per 10L of water using calcium carbonate or when
using potassium carbonate (K2CO3 is 43.4% carbonate @ 100% purity) 0.83
grams per 10L or when using baking soda (sodium bicarbonate or NaHCO3
which is 76.24% bicarbonate) would equate to 0.762 g/10L. As a
recommendation, I tend to suggest that baking soda is ideal for increasing
alkalinity in hydroponic systems where RO water is used. Firstly it is easy to
access at high chemical purity through supermarkets. Secondly, when used at
the suggested rate of 0.47grams per 10 litres it contributes approximately
13.5ppm of sodium (Na) to the nutrient solution which is well within tolerance
range for plants being grown in hydroponic systems (and less Na than is
typically found in mains water supplies). On the other hand, while some have
recommended the use of potassium carbonate and calcium carbonate for pH
buffering water, both of these components will add calcium or potassium to the
working solution at ppm which may contribute to nutrient imbalances."
original article:
Hope this helps someone
. . .
I too have been having an issue with maintaining a stable PH. I did some research into buffering (remembering my saltwater reef days) I hope this helps. The short version is that if you are using RO water, a gram of baking soda per 5 gal/20 liter will set your alkalinity to about 60-70 ppm. I used a hanna freshwater tester to figure it out.
Hanna Checker on Amazon
. . . "This one only applies to those of you who are using RO water and relates to
water alkalinity and its ability to buffer pH. For those of you who are using mains
water this material doesn’t apply due to mains water often possessing high
alkalinity (often far too high) values. Alkalinity is best expressed in this case (so
as not to confuse things) as the buffering capacity of water. That is, the
alkalinity of water is related to the pH, but it is actually a different parameter. It
is a measure of the capacity of the water to resist changes in pH. Don’t confuse
“Alkalinity” with “Alkaline” (which relates to an alkaline pH of above 7.0). The
higher the alkalinity, the more acid can be added without considerably changing
the pH. This is because the bicarbonates (HCO ) and carbonates (CO )
react with the hydrogen ions (H ) contributed by the acid, preventing them from
dropping the pH. Alkalinity is typically expressed as the equivalent concentration
of calcium carbonate (CaCO ). The ideal range for alkalinity as ppm CaCO is
expressed as 40-60 ppm, with 20-80 ppm being the outside range. Calcium
carbonate is 60% carbonate and 40% calcium at 100% purity. Thus to equate
60 ppm CaCO into how much carbonate this represents 60 (ppm) – 40%
(calcium) equals 60% Carbonate, so 60% of 60ppm = 36ppm carbonate. This
would equate to 1 gram per 10L of water using calcium carbonate or when
using potassium carbonate (K2CO3 is 43.4% carbonate @ 100% purity) 0.83
grams per 10L or when using baking soda (sodium bicarbonate or NaHCO3
which is 76.24% bicarbonate) would equate to 0.762 g/10L. As a
recommendation, I tend to suggest that baking soda is ideal for increasing
alkalinity in hydroponic systems where RO water is used. Firstly it is easy to
access at high chemical purity through supermarkets. Secondly, when used at
the suggested rate of 0.47grams per 10 litres it contributes approximately
13.5ppm of sodium (Na) to the nutrient solution which is well within tolerance
range for plants being grown in hydroponic systems (and less Na than is
typically found in mains water supplies). On the other hand, while some have
recommended the use of potassium carbonate and calcium carbonate for pH
buffering water, both of these components will add calcium or potassium to the
working solution at ppm which may contribute to nutrient imbalances."
original article:
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Hope this helps someone