TA, pH balancing and hot tub pillows

[cschnurr]

My hot tub numbers are:
Bromine 5
pH 7.6
TA 85

My hot tub has pillows that detach from the tub.
They look like they are made with some type of plastic/foam.
Last week I noticed that the pillows were shedding foam debris into the tub.

When I went to the pool store where I purchased the tub, they indicated it was likely due to pool chemistry.
Even though I test my water using my own kit, I occasionally drop in to have them test for me as well while I'm purchasing equipment or supplies.
The stores recommended TA for a hot tub is 100-150, my tub is typically around 85.
So every time I go in, they recommend increasing TA with buffer/baking soda.
They indicated that the low TA could cause pH to fluctuate out of range.

Whenever I've tried to get to their targets, I fail.
I'm finding impossible to achieve a target TA of 125 and keep pH in range. (similar to Going Crazy with ph/TA)
TA and pH both increase with baking soda, and decrease with acid.

I find it hard to believe that pillows are shedding from low TA causing pH fluctuations.
Is it more likely that they are shedding from the addition of Baking Soda trying to achieve TA=125 which spikes the pH out of range.

I'm afraid my warranty claim for pillows might be stuck between what makes sense on this forum vs pool store TA targets.
Any advice?

 

[kimkats]

I wonder where they get their numbers from. I am going to look for the papers that explain how TFP's TA level was found. If anyone else finds them first feel free to post them up!

 

[zea3]

How old are these pillows? Doing a brief search they only last a couple of years and ozonators keep popping up as a reason for accelerated deterioration.

 

[cschnurr]

Pillows are a year old, and cost $25 Cdn each, so its not a big deal.
I was also wondering about the 100-150 TA, next time I'm in, I'll ask them.

This post made me question my understanding of TA in general.
When I change water my TA is high (around 200).
As the tub is used, aeration causes pH to rise and I add acid to keep pH down.
The regular addition of acid makes the TA drifts down to its 'sweet' spot to a point using the tub no longer drives pH up.

If I simply address the acid demand by adding acid, do I even need to worry about TA?

 

[zea3]

No, the main reason to adjust TA is to stabilize pH.

 

[cschnurr]

I had a discussion with the pool store and told them that the manufacturer's recommended TA value was 80-120.
She pulled out her supervisor who then said, "I know, my own TA is typically around 85.", and then apologized for her newbie.

I'm just noting that if you take action based on pH, then TA will find its own sweet spot.
I can't think of a scenario where one would do something based on TA measurement alone.

Thanks for the replies.