PH always goes up after every use, normal? help please

[jrspa]

Have a 500ish gallon tub installed about a month ago.  Really got no help from the installer on the maintenance other than to check it.  I use the Taylor drops, have a floater inside with bromine and been between the 204 range.  

TA I keep over 60, when it dips to 50, I add enough baking soda to bring it up to 80.

PH always goes over 8 after EVERY use.  I read on the jets outgassing stuff but I need to add acid (at least 1 oz) after every use.  Is that normal?  

Had PH down to 7.5 yesterday, 2 of us were inside for about 30 minutes, but less then 10 minutes of jet time.  

We do have a ozone thing.  

With the amount of time we spend in the spa, I seem to be adding a lot of chemicals to keep the numbers right, but I don't know what else to do.  It feels like I am throwing $$ down the drain and might be hurting the spa.  The water is clear and was told by the retailer, "water smells normal".   

Talked to a few people at work with spas and they add chemicals once or twice a month.  I have no idea what their numbers are but I feel lost.  Please advise

[Crowbait]

Hi Jrspa,

I will try to answer based on the info I have learned here on this forum and my experience...   anyone feel free to correct me!

It sounds like your TA is high compared to your water CH.  So because your TA is higher than necessary,  when you aerate, it raises your pH.

A TA of 80 is a guideline for starters and will be relative to your water hardness(CH).  The higher the hardness, the lower the TA will likely need to be. 

For instance, on my 450 gal tub, with my CH at 150, my pH is not stable until I drop down to around 55-60ppm TA.  Any higher than that, and my pH climbs everytime I use the jets/blower.  This is without using borates.

Basically I check my CH, check my TA, and then check my pH.  If I run the jets/blower for 30 minutes and the pH climbs, I add a little acid and try again, checking only pH.  Once my pH stays stable after adding the right amount of acid, I stop and check my TA again and record it. 

Once I find the sweet spot, my pH seems to stay pretty stable. 

I have now started using borates in the form of 'ProTeam Gentle Spa'.  This is supposed to prevent pH rise from aeration, and make the water feel 'nicer.' 

Maybe I will be able to have a higher TA and maintain my pH now that I am using 'Gentle Spa'..

Good Luck!

 

 

[chem geek]

The TA is not related to CH, at least not for the rate of rising pH.  Just keep the TA lower and if you have it very low such as 50 ppm then you can use borates to supplement pH buffering.  Though this can be done using Gentle Spa, you could buy boric acid directly from Duda Diesel or The Chemistry Store (link currently broken).

[jrspa]

Thanks for the info.  

Just a quick update.  I had 7 people inside of it with the jets running for awhile, shocked it when I was done and tested it the next day.  Ph was 7.5ish.  First time ever that I was able to use it and not have to add acid.  

3 days later, my 3 nephews used it, next day perfect.  

My only concern is the TA is at 30.  Is that ok as long as the PH isn't spiking or do I need to bring it up?

[dlleno]

I ran with TA=30 with good success but keep in mind that 30 is very close to a handing you a precipitous drop in pH which you don't want. So you gotta watch things very closely when you get that low.   I stopped chasing TA as a  number to achieve and controlled pH with acid until TA dropped to 30-40 at which time pH was easier to control.  yes the duda diesel borates are fantastic. 

[chem geek]

So long as you are not adding net acidic chemicals, a low TA is OK particularly if you are using 50 ppm Borates for additional pH buffering.  If you are using chlorine then you should also have some CYA in the water and that provides some additional pH buffering.