Hello. New here. Love this forum! Question. Added liquid shock to pool last night. Free chlorine at 11 ppm now. Alkalinity at 40. (Using Taylor fas dpd to test) Ph at 7.4. Want to add about 9 lbs of sodium bicarbonate To raise alkalinity. Will do 1/2 now. 1/2 later. This sound right? Will it raise the ph too much? Is it ok to add while chlorine is high? Don't want to mess anything up....pool is crystal clear now. Thanks. Oh and cya at 30. New fill new liner this year
Using sodium bicarbonate
- Thread starter Lcts
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Welcome! 
Sounds like a plan. Scroll down towards the bottom of poolmath to Effects of Adding Chemicals and it will show you what you can expect for pH rise, roughly.
Sounds like a plan. Scroll down towards the bottom of poolmath to Effects of Adding Chemicals and it will show you what you can expect for pH rise, roughly.
9 pounds of sodium bicarbonate in 12,000 gallons would raise the TA by 53.5 ppm which would get you over 90 ppm which sounds a bit high since you don't know if your pH will be stable at that level. Since you have a vinyl pool, you do not need to saturate the water with calcium (CH) or carbonate (TA, pH) so I'd shoot for 70 ppm instead and add only 5 pounds. If you find that your pH tends to drop over time, you can then later increase the TA more.
Yes, you can add pH and TA adjusting chemicals anytime, even when the chlorine is high (though you usually can't get an accurate pH reading when the chlorine level is above 10 ppm, at least not without diluting with distilled or deionized water).
Yep, if your FC is over 10, it will throw the pH test results off and you will not get a good reading.
Why is your FC up that high?
Why is your FC up that high?