Baking Soda

[powerplay]

Hi,
On an initial water fill my ph is 6.8 and alkalinity is 80. I use dichlor. I want to use baking soda to raise both to acceptable levels. What is an approximate formula/ rule of thumb of a quantity to add. The tub is 520 gallons. How long will it take before I can recheck the readings.
Thank you

[Vinny]

Put 6 tablespoons in and give it a 1/2 hour to mix. Adjust more or less as needed. The PH may go up a lot (probably not but be on the safe side). I don't think there's a formula.

Once you get used to the amounts your tub/water needs, you'll add the right amount from the start.

[wmccall]

I disagree on the 1/2 hour.   Anytime I make a PH adjustment, I wait 24 hours to check again.   That avoids having a runaway condition when you add more chemicals because your reading hasn't caught up with the last chemicals you had added.  

[Chas]

I'm going to go with Bill on this one: wait at least four or five hours, and 24 is certainly the best. pH and TA will tend to take a jump and then settle a bit.

Bill - your avatar is missing a word I think.

[Vinny]

I guess it's time to change the way I'm doing things!

[Brewman]

It's also time for Bill to add the missing word to his avatar.  IF he's not too busy buying drinks for his curling buddies!

[Tman122]

My water starts with almost the same readings as yours 6.8-7.0 PH and 60-70 TA I use 4-6 OZ's of baking soda in 3 additions over a week to get my water where it needs to be. Then it takes about 1-2 OZ's every 5-6 weeks to maintain it.