Adjusting pH and TA

[K9Chris]

Just checking everyone thoughts on how I should approach balancing my water. First time pool owner here and am opening a poorly maintained pool for the first time. My plan is to add roughly 10.8 lbs by weight of soda ash to increase the pH to 7.6 and then retest to figure out the amount of baking soda I should add to increase the TA. From what I understand CH isnt as important in my case because I do not own a heater (needed for warranty) and my pool is vinyl lined.

Does this seem right, oh great pool gurus?

CYA- 70
FC- 8.5
pH- 6.4ish? 12 drops of base demand needed to get to 7.4 pH
TA- 40
CH- 50

 

[Richard320]

First question: is the water green or cloudy? Because if it is, you'll want to SLAM, and that's very hard to do at 70 CYA. So if some water replacement is in the near future, why treat the water only to pump it out?

If you are just going to raise the crashed pH & TA (Which is usually caused by a steady diet of trichlor pucks and dichlor shock) then only add 3/4 of what it says and recheck it in a day. Your pool may not be as big as you think and you don't want to go way over.

Low CH is not a problem for the vinyl, but it may allow the water to foam which can get annoying. Some small amount of CH (but more than you have now) will stop that.

 

[K9Chris]

Sorry! I've already SLAMed my pool. It was indeed difficult to do. I had to bring my FC up to 28 and it took 7 days for to pass all three criteria. My original CYA was somewhere around 150. I decided to leave it at 70 this season and try and lower it further next year. I will add 3/4 of what it says. Should I add both the soda ash and the baking soda at the same time to raise pH and TA or should I do the soda ash for the pH first?

 

[Richard320]

Sorry! I've already SLAMed my pool. It was indeed difficult to do. I had to bring my FC up to 28 and it took 7 days for to pass all three criteria. My original CYA was somewhere around 150. I decided to leave it at 70 this season and try and lower it further next year. I will add 3/4 of what it says. Should I add both the soda ash and the baking soda at the same time to raise pH and TA or should I do the soda ash for the pH first?

I'm kind of curious why you didn't set the pH to 7.2>7.5 before the SLAM. That's one of the prerequisites.

Anyway, no, don't go dumping mass quantities of multiple chemicals in back to back. If you scroll down to the bottom of poolmath where it says Effects Of Adding Chemicals, you'll be able to see how much TA you'll be adding with the washing soda. Ignore the pH change down there -- it's only correct within very narrow parameters. But the TA rise will be right. Raise pH and then recheck it all and see what you need.