John P Coates
Member
Hi Folks,
In my tropical planted tank (including fish), I use RO water to which I add Tropic Marin Re-Mineral Tropic salts. I also add sodium bicarbonate to bring the KH and GH to 5°dH and 7°dH, respectively. In as little as 9 days, the KH has increased to 6.5°dH. When KH = 6.5°dH, pH varies from 7.7 to 7.9 as CO2 is injected throughout the day. I would like to get pH down to 7.0 or slightly less but the higher KH is making this difficult.
As an experiment, I made up a litre of water using RO to which I'd added sodium bicarbonate only. I made this up to achieve KH = 2°dH. To my surprise, I also found that, after a week or so, the KH had risen to 3°dH. During that time, the water has been stored in a plastic bottle (with lid) at room temperature in a dark place. KH was measured using NT Labs and Nutrafin test kits.
What is causing KH to increase over time? Isn't KH supposed to be stable?
JPC
In my tropical planted tank (including fish), I use RO water to which I add Tropic Marin Re-Mineral Tropic salts. I also add sodium bicarbonate to bring the KH and GH to 5°dH and 7°dH, respectively. In as little as 9 days, the KH has increased to 6.5°dH. When KH = 6.5°dH, pH varies from 7.7 to 7.9 as CO2 is injected throughout the day. I would like to get pH down to 7.0 or slightly less but the higher KH is making this difficult.
As an experiment, I made up a litre of water using RO to which I'd added sodium bicarbonate only. I made this up to achieve KH = 2°dH. To my surprise, I also found that, after a week or so, the KH had risen to 3°dH. During that time, the water has been stored in a plastic bottle (with lid) at room temperature in a dark place. KH was measured using NT Labs and Nutrafin test kits.
What is causing KH to increase over time? Isn't KH supposed to be stable?
JPC
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