Alkalinity for Hot Tub

[JodieM]

Just did my spring dump, clean and refill on my 250 gal stand alone hot tub. My fill water alkalinity is a whopping 440! What is the recommended TA for a hot tub? And is the only way to get this TA down to reduce PH and aerate to get it back up and repeat until TA comes down? Here are my current fill water levels with a TF100 kit.
FC 0
PH 7.5
CH 200
TA 440
CYA 0

 

[TheCatLady]

Yes, pretty much acid and aerate is your best bet.
TA should be between 50 and 90, with the lower end being better to keep ph steady in a hot tub, since aeration increases Ph.
It's a long and tedious process if you need to decrease so much, I've just done it last week and it took me more than half a day to get it from about 220 to around 80 so that I can balance the water. The rest I just do over time.
If you plan to add borates, add them last, after you get your TA in check. Borates will increase acid requirement to drop Ph/TA.

 

[Mdragger88]

Yes, The only way to lower ta is acid which also lowers ph.
The only way to increase ph without also increasing ta is aeration.

Lower Total Alkalinity

A lower Total Alkalinity level can help a pool owner stabalize their pH increase. We'll explain how to lower TA with a little help from muriatic acid.

www.google.com

A ta of 50/60 is ideal to moderate ph rise but that’s not always possible for everyone to achieve in a short period. Just getting below 100 can really help. Luckily the aeration part is pretty quick in a hot tub & it takes minutes each time vs days in a pool.
You don’t have to be @50 -90 before adding borates, it’s just the most ideal for the reason mentioned above.

 

[Krulligo]

I keep my alkalinity at 50ppm and my pH hasn't changed from 7.7 in months. It's completely locked in with no fluctuation (with added borates). I measure pH once a week.

I don't know how you are getting such a low pH measurement with such high alkalinity. Even for me when TA is over 100, my pH jumps to over 8.2 in a matter of a few hours

 

[JodieM]

I got my TA down to 60. My PH is 7.5. I’ll be out of town for the wknd, I’ll check it when I get back. Fingers crossed PH hovers around 7.5 while I’m gone and just stays put with my new TA level. Thanks for everyone’s help.

 

[Mdragger88]

I got my TA down to 60. My PH is 7.5. I’ll be out of town for the wknd, I’ll check it when I get back. Fingers crossed PH hovers around 7.5 while I’m gone and just stays put with my new TA level. Thanks for everyone’s help.

It may not stay put (cuz aeration) but the frequency of rise should be lessened. I don’t have borates in right now & with a ta of 50/60 my ph will hang at 7.8 for days.

 

[Methuselah]

Being gone, aeration should be at a minimum (just don't leave the air valves open).

BTW, ph might "decide" to hover around 7.8 or 7.9. That's not going to hurt anything

 

[KayBee39000]

Central Indiana person here! I just texted the groundwater in Carmel and it’s 350 for hardness and alkalinity! Crazy

 

[JodieM]

Central Indiana person here! I just texted the groundwater in Carmel and it’s 350 for hardness and alkalinity! Crazy

Hello KayBee in Carmel! I’m in Brownsburg.

 

[KayBee39000]

I saw that! I never realized how special our water is here in central Indiana - until I got a hot tub!!