High Ta, Normal Ph

[Tommytub]

New owner of Sundance Marin, 335 gallons,

During 1st month of ownership, I struggled with the PH & TA balancing, while using PH Down. I started with PH in excess of 8.2 and TA @ 290. Needless to say, I reduced my TA at one point to 80, but my PH was still high. Finally after 3 weeks I dumped water.

Today, after filling my with no chemical add, my PH is 7.8 & TA at 290. My calcium is at 300. I used 3 tablespoon of PH Down and my next reading was PH at 7.2, TA at 280.

I seemed to be having the opposite problem as I did with my 1st fill. Before I add more chemicals, what do you recommend? How do I lower TA and while maintain the PH level?

[waterbear]

New owner of Sundance Marin, 335 gallons,

During 1st month of ownership, I struggled with the PH & TA balancing, while using PH Down. I started with PH in excess of 8.2 and TA @ 290. Needless to say, I reduced my TA at one point to 80, but my PH was still high. Finally after 3 weeks I dumped water.

Today, after filling my with no chemical add, my PH is 7.8 & TA at 290. My calcium is at 300. I used 3 tablespoon of PH Down and my next reading was PH at 7.2, TA at 280.

I seemed to be having the opposite problem as I did with my 1st fill. Before I add more chemicals, what do you recommend? How do I lower TA and while maintain the PH level?

There really is only one way to succesfully lower TA.....Here it is step by step (You must have a drop based test kit to do this, test strips do not have the precision needed!)

1 drop the pH to 7.0 with acid

2 start aerating the water (turn on all you blowers and venturis for the jets). As you aerate the pH will rise because of the outgassing of carbon dioxide gas.

3 test pH as you aearate and when it climbs to about 7.6 retest TA. If TA is still to high repeat process

It can take anywhere from an hour to a day of aeration to cause the pH to rise back up. it depends on how well your tub will aerate the water.

For a brief explanation of why this works....when you add the acid to drop the measureable TA you convert part of the carbonate/bicarbonate buffer we call TA to carbonic acid (carbon dioxide dissolved in water, think club soda)

when you aerate you drive off the carbon dixoide( think shaking a bottle of club soda to make it go flat) which reduces the amount of carbonic acid and causes the pH to rise with no impact on the TA

If your TA needs to be lowered a lot there is a faster way if you have a good drop based test kit and are familiar with it's use....keep the pH at 7 by the additon of acid while you aerate and keep testing TA until it is where you want it then stop adding acid and let the pH rise by the aeration....You will end up the the pH and TA exactly where you want them

[Tommytub]

There really is only one way to succesfully lower TA.....Here it is step by step (You must have a drop based test kit to do this, test strips do not have the precision needed!)

1 drop the pH to 7.0 with acid

2 start aerating the water (turn on all you blowers and venturis for the jets). As you aerate the pH will rise because of the outgassing of carbon dioxide gas.

3 test pH as you aearate and when it climbs to about 7.6 retest TA. If TA is still to high repeat process

It can take anywhere from an hour to a day of aeration to cause the pH to rise back up. it depends on how well your tub will aerate the water.

For a brief explanation of why this works....when you add the acid to drop the measureable TA you convert part of the carbonate/bicarbonate buffer we call TA to carbonic acid (carbon dioxide dissolved in water, think club soda)

when you aerate you drive off the carbon dixoide( think shaking a bottle of club soda to make it go flat) which reduces the amount of carbonic acid and causes the pH to rise with no impact on the TA

If your TA needs to be lowered a lot there is a faster way if you have a good drop based test kit and are familiar with it's use....keep the pH at 7 by the additon of acid while you aerate and keep testing TA until it is where you want it then stop adding acid and let the pH rise by the aeration....You will end up the the pH and TA exactly where you want them

First I have a (1) bubbler (blower) and (2) jet pumps with Air Controls to adjust the pressure. Please clarify which or all should be used in this process.

Also this process is while the PH down is added? If so, am I correct in assuming that once the PH & TA have been established, that using the blower/pumps during normal use will not cause the PH to rise, only during the chemical add!

Thanks for your help!!

[waterbear]

First I have a (1) bubbler (blower) and (2) jet pumps with Air Controls to adjust the pressure. Please clarify which or all should be used in this process.

I would use all of them. The more aeration the faster the process works

Also this process is while the PH down is added? If so, am I correct in assuming that once the PH & TA have been established, that using the blower/pumps during normal use will not cause the PH to rise, only during the chemical add!

Lowering the pH lowers the TA. (It converts part of the bicarbonate/carbonate in the water to carbonic acid. The bicarbonate/carbonate part of the buffer system is what we measure as TA.) Aerating raises the pH without affecting TA (By lowering the carbonic acid component of the buffer system).

Thanks for your help!!

Because of the constant aeration in a hot tub you will always have a TA that will drop.(and the acids given off by the bodies soaking in them also cause the pH and TA to drop) This is easily remedied by the addition of baking soda (EXACTLY the same thing as total alkalinity increaser!) I personally keep the TA in a tub around 100-150 ppm if the tub gets a lot of use. When the TA is on the low side and the pH is where you want it then add the baking soda, reajust the pH since the baking soda will cause it to rise slightly, and you are good to go again. This is why a good test kit and regular water testing is important. I would test the pH at least a few times a week and the TA weekly or every two weeks. Calcium can be tested montly since it doesn't change that much once it has been adjusted unless you have a lot of evaporation and your fill water is either very hard or very soft. Also if your fill water has a high TA, which yours seems to have, then the water that you add to make up for evaporation will probably keep your TA in line once you get it adjusted initially.