Last year my pool's alkalinity was in the 150-175 range and CYA was around 70, which sound high. Yet my pH was very stable and I did little or no aerating and certainly never had to add acid. I've always used the Taylor chemicals to balance my pool throughout the season.
This year is different. I started off with the recommended alkalinity of 100. My pH has continually been decreasing and I've had to aerate many times when my pH has been getting down to 7.2 to 7.3. I'll get the pH to 7.6 and a week later (or less) I'll have to aerate again. My CYA has been in the 30-50 range but I recently increased it to 50. I usually have a solar cover on my pool since it is in part-shade. I would like to stabilize my pH and it seems that I should vastly increase my alkalinity to fix these problems.
I have never used washing soda before, but it seems that it will have the dual benefit of raising my pH and alkalinity at the same time. However, the PoolMath calculator gives contradictory advice about adding it. Here is a screenshot of all my chemical levels (please note that I could not paste it here because its size is too large):
https://image.ibb.co/fudNt9/PoolMath.gif
Translation: FC=8.5, pH=7.4, TA=70, CH=90, CYA=50, Salt=unknown, Borate=0, Temp=80. Suggested FC min=4 max=8. I have no way of measuring borates or salt, but I never add borates and we have soft city water around here. Pool water has been partially replaced several times, so I'm not worried about salt.
In the image, I circled two areas that gave me contradictory information about adding washing soda. In the top circle, it advises me to increase the pH from 7.4 to 7.6 I should "add 2.1 oz by weight...of washing soda." But in the bottom circle, after adding in my own number, it advises me that "adding 32 oz of washing soda will raise pH by 2.24 and raise TA by 73." If I change the bottom figure to add 2.1 ounces of washing soda, it says that doing so "will raise the pH by 0.15 and raise TA by 4.8." These statements both can't all be true. You can't add 2.1 ounces of washing soda to raise the pH by 2.0, or instead add 32 ounces of the same substance to raise the pH by 2.24. That's mathematically impossible.
So which is it? Should I add 2.1 ounces or 32 ounces of this stuff? And is this a known issue with PoolMath?
This year is different. I started off with the recommended alkalinity of 100. My pH has continually been decreasing and I've had to aerate many times when my pH has been getting down to 7.2 to 7.3. I'll get the pH to 7.6 and a week later (or less) I'll have to aerate again. My CYA has been in the 30-50 range but I recently increased it to 50. I usually have a solar cover on my pool since it is in part-shade. I would like to stabilize my pH and it seems that I should vastly increase my alkalinity to fix these problems.
I have never used washing soda before, but it seems that it will have the dual benefit of raising my pH and alkalinity at the same time. However, the PoolMath calculator gives contradictory advice about adding it. Here is a screenshot of all my chemical levels (please note that I could not paste it here because its size is too large):
https://image.ibb.co/fudNt9/PoolMath.gif
Translation: FC=8.5, pH=7.4, TA=70, CH=90, CYA=50, Salt=unknown, Borate=0, Temp=80. Suggested FC min=4 max=8. I have no way of measuring borates or salt, but I never add borates and we have soft city water around here. Pool water has been partially replaced several times, so I'm not worried about salt.
In the image, I circled two areas that gave me contradictory information about adding washing soda. In the top circle, it advises me to increase the pH from 7.4 to 7.6 I should "add 2.1 oz by weight...of washing soda." But in the bottom circle, after adding in my own number, it advises me that "adding 32 oz of washing soda will raise pH by 2.24 and raise TA by 73." If I change the bottom figure to add 2.1 ounces of washing soda, it says that doing so "will raise the pH by 0.15 and raise TA by 4.8." These statements both can't all be true. You can't add 2.1 ounces of washing soda to raise the pH by 2.0, or instead add 32 ounces of the same substance to raise the pH by 2.24. That's mathematically impossible.
So which is it? Should I add 2.1 ounces or 32 ounces of this stuff? And is this a known issue with PoolMath?