What’s with the low Alk using Bromine?

[Vegas]

I Recently started using bromine in my tub and I’m having an issue keeping the Alkalinity in range between 80-120ppm.

This is my second fill with Bromine after using Chlorine for a year and a half. I never had this issue when using Chlorine.

Little background on the tub. 400 gallon,city water, ozone, circulation pump.

Fresh fill with new filters, bromine salt to build the base, 2 oz MPS, 2 bromine tabs in floater. 
 

procedure was after the Water fill. I used dry acid to bring down the pH to 7.6. ( 4 ounces in total ) I then added the bromine salt, the MPS, and the floater. Ph then shot up to over 8.0 added another 3 ounces and then decided to take in a water sample to the pool store 

currently the reading are:

8.0 ph, 62 Alk, Calcium 158, Bromine is 8.42

 Now I’ve read in this form that keeping alkalinity between 50 to 60 is not a problem.  However of course everything were taught says the alkalinity should stay between 80 and 120. 
 

what’s your thoughts on my next steps bring the pH down and not worry about the alkalinity? or fight the alkalinity and pH to get them in traditional ranges? 

[dashmer]

I am thinking your pH reading is wrong. All of the products you are using are acidic, so you should not have a pH that high with the TA that low. High sanitizer levels can wash out pH readings.  You should wait until your sanitizer level drops down into the normal range and retest your pH.  What are you using for a test kit? 

A TA of 50 might be on the low side when using the products you are using.   There is a good sticky in this forum on setting up bromine tubs that probably lists the desired TA and pH.  Check the top of the list of topics.

[Vegas]

The reading I posted is directly from Leslies Pool store. I was doubting my Taylor drop test key due to the high bromine so I had them test. 

[waterbear]

On 3/31/2022 at 1:49 PM, Vegas said:

8.0 ph, 62 Alk, Calcium 158, Bromine is 8.42

Other than the fact that your bromine is a bit high these numbers look good for a bromine spa. MPS is acidic so it will deplete TA so when it drops below 50 ppm use baking soda to bring it up. 50 to 70 ppm is a sweet spot for most spas.

High sanitizer levels can cause DPD tests to bleach out and your pool store is using either testing discs or strips with meter to give you results like that. IF your Taylor kit is a k-2006 (FAS-DPD testing for bromine or chlorine ) then bleach out is not really a problem unless your bromine is really through the roof and I would trust it over the pool store test. IF it's a K-2005 (DPD testing) then it can and will bleach out at moderately high sanitizer levels and indicate that your bromine (or chlorine) is much lower than it actually is. This can affect pH and TA readings since high sanitizer will cause inaccurate pH readings (pH will seem to be much higher than it actually is because the pH indicator, phenol red, is converted into bromophenol red or chlorophenol red both of which have the same color changes as phenol red but at a much lower pH range and the purple red color that indicates a pH of 8.2 or higher with phenol red indicate a pH of 6.7 or higher with chlororphenol red or 6.8 or higher with bromophenol red. High sanitizer can also bleach out the indicators used for TA testing leading to off resuts, particularly with colormetric tests (read with a meter) vs titration tests (such as Taylor's).

[Vegas]

1 hour ago, waterbear said:

Other than the fact that your bromine is a bit high these numbers look good for a bromine spa. MPS is acidic so it will deplete TA so when it drops below 50 ppm use baking soda to bring it up. 50 to 70 ppm is a sweet spot for most spas.

High sanitizer levels can cause DPD tests to bleach out and your pool store is using either testing discs or strips with meter to give you results like that. IF your Taylor kit is a k-2006 (FAS-DPD testing for bromine or chlorine ) then bleach out is not really a problem unless your bromine is really through the roof and I would trust it over the pool store test. IF it's a K-2005 (DPD testing) then it can and will bleach out at moderately high sanitizer levels and indicate that your bromine (or chlorine) is much lower than it actually is. This can affect pH and TA readings since high sanitizer will cause inaccurate pH readings (pH will seem to be much higher than it actually is because the pH indicator, phenol red, is converted into bromophenol red or chlorophenol red both of which have the same color changes as phenol red but at a much lower pH range and the purple red color that indicates a pH of 8.2 or higher with phenol red indicate a pH of 6.7 or higher with chlororphenol red or 6.8 or higher with bromophenol red. High sanitizer can also bleach out the indicators used for TA testing leading to off resuts, particularly with colormetric tests (read with a meter) vs titration tests (such as Taylor's).

Thank you very much! That was a lot of information I did not know