OFFICIAL water chemistry guidelines-what are they?

[Nitro]

I have a similar problem but nothing to do with my PH...

That's about the funniest thing I heard all week.

[Gomboman]

Never thought too much about aeration before. I just tested my water from the tap with my Taylor test kit--haven't done this in years. Here are my results: PH = 8.0+, Alk = 100, Cal = 90

Normally I throw in a little dry acid with a new fill and the PH usually drifts down on it's own after a couple weeks. My calcium has always been low for some reason. When the tub was new I used to add calcium increaser but I don't hassle with it anymore. Any huge concerns if my calcium is always under 100?

[Mr._Bubbles]

If you have a problem keeping pH up, you may want to raise your TA with Baking Soda. Where is your TA at now?

Also, Dichlor is acidic and will lower TA/pH over time. If you don't raise your TA periodicly, it will get too low.

I haven't tested TA. I'll keep the Baking Soda idea in mind.

[Vinny]

When I have a fresh fill and test my water both PH and alkalinity are low. I didn't test my alkalinity out of the tap recently but the PH is below 7.0. This is without aeration or dichlor or anything else - just plain water. I don't add anything but baking soda and my PH along with alkalinity goes up - this is done with all pumps on and no air for about 20 minutes and I check the PH hours later and add more baking soda if needed. My PH stays there for weeks and then starts to go down, when it gets to 7.2 or so I add more baking soda and my Ph goes back up.

I don't doubt what you say about aeration but my PH has never went up - always down. I do understand that the overall effect of dichlor is an acid result and this along with using MPS that has a PH of about 4 will bring down the PH in the water. I attribute my PH recently going up from 7.2 to 7.4 due to the amount of bleach that I put in (PH of about 13) and the fact my alkalinity is at 80 and not 120. I attribute it to the bleach ONLY because I added so much to the tub that the bleach that wasn't used up through any type of reaction (sanitizing or oxidizing) was disipated due to the heat and the overall effect was for the PH to go higher. I never have the tub running with air since I don't want to inject cold air into the hot water when I am not using it - air wasn't a factor this time of the PH rise.

By all logic I agree that my PH should not be affected too much by adding baking soda but it does. After the initial 20 minutes of mixing I have a circ pump and my tub only runs the main pumps for 1 or 2 minutes a day without air. In the past I have had a PH of 7.8 and an alkalinity of over 120 and my PH still creaped down, it just took a little longer to get there. I will say that I don't use my tub that often and when I use the correct amount of bleach my PH stayed rock steady for a long time.

To the point of not knowing where the alkalinity is - no I didn't know exactly where it was but at a PH 7.2 I knew it was about "in range", which it was. I guess you test your water all the time ... I've gotten past that point only because my water behaved the same way pretty much all the time I tested it. At 7.2 I dump in some more baking soda and both my PH and alkalinty go higher. I could test my PH and alkalinity once I add it but I only test the PH hours later to see if it has come up to where I want it. If it goes higher because of aeration -  couldn't tell you but it stays there for weeks using dichlor or months using bleach. I've come to the realization that "worrying" over the water vs understanding what MY water is doing was just a waste of my time. I agree 100% that everyone who has a pool or spa should understand water chemistry and I do understand that balanced water is the ideal solution but even balanced water has a range in which everything is OK. There are no finite numbers to balance water - once I understood this concept I started not nitpicking.

Personally, I am more concerned about the sanitation aspect of the pool and spa vs if they are at 7.2 or 7.8 PH - both are in range. Also, for me a alkalinity of 80 is no big deal vs 120 IF the PH falls into place. I asked questions of chemgeek months ago about bleach and he answered my questions to my satisfaction and now I use it.

Vinny,

80 ppm TA is a lot lower than 120 ppm, which is technicaly still "in range". I can guarantee you if you raise your TA to 120, your pH will keep rising from aeration. In my earlier post I said, "The best way to keep it (TA) from doing that (creep) is to lower your TA (60-80 ppm).". My point was (and is), "Don't expect your pH to stay between 7.4-7.6 if your TA is 125 ppm.". And you will not find that information in the Taylor books.

When I said, "Well, if you haven't been measuring TA, it's hard to tell where it is.", I meant it's hard for ME to tell where YOURS is. I guess it was hard for you to tell too, because you had to measure it to know. FYI, I rarely need to check my TA, because I know where it's at (60 ppm). The only thing I check regularly is FC, and sometimes pH.

I was under the impression your TA was higher (~120), because you seemed to disagree with my above post. Also, you said, "From what I learned the higher the TA (within reason) the more it locks in the PH which is why you need to use a lot of acid in order to lower PH with high alkalinity." That is true, but doesn't account for aeration. A TA above 100 will make it very difficult to keep pH < 8.0 in a hot tub with jets/air.

If you want to prove this fact for yourself, try this. Add Baking Soda to your tub to raise TA to 120, (about 3 oz). Measure your pH. Then kick the jets and air on for 30-60 mins. Then measure your pH again. Your pH will be much higher then before you turned on the jets. This is because aeration raises pH more with a higher TA. But I wouldn't recommend doing this until right before your next drain. Otherwise, you'll have to add acid to bring your TA/pH back down.

Lastly, Baking Soda has little effect on pH directly. Baking Soda raises TA, not pH. However, because your TA is higher, that causes your pH to rise from aeration. The reason why your pH doesn't rise in your pool from the addition of Baking Soda, is because your pool has a lot less aeration than your hot tub. Therefore, a higher TA in a pool won't effect pH as much as it does in a hot tub.

[Nitro]

Vinny,

You should do whatever works for you. I was just pointing out to the OP that having a TA of 120 ppm, while still in range, could cause pH creep issues from aeration. If my my TA is even 100 ppm, my pH creeps up too much. I found that with my TA at 60 ppm, my pH is rock solid at 7.8, and I don't need to add any Acid or Baking Soda after the initial dose.

Also, I don't test TA all the time. I only test it when I fill the tub and adjust it, which was over a month ago. I just keep an eye on pH to make sure it stays at 7.8. If my pH does drift, I adjust TA, not pH. If your TA is well tuned, your pH will be stable.

I agree, Sanitization is very important, but the OP was referring to Water Balance in this thread. BTW, I also learned to use Bleach from ChemGeek. He is the expert on that method, and Water Chemistry in general.

[Nitro]

Never thought too much about aeration before. I just tested my water from the tap with my Taylor test kit--haven't done this in years. Here are my results: PH = 8.0+, Alk = 100, Cal = 90

A lot of people don't know about aeration causing a rise in pH. I only know it because I learned it on another board. It can cause a lot of issues if you're using bleach to sanitize your tub. If you use Dichlor it's not as apparent, because Dichlor is acidic, and lowers TA/pH over time anyway. However, bleach is relatively pH netural, so it becomes more apparent.

Normally I throw in a little dry acid with a new fill and the PH usually drifts down on it's own after a couple weeks. My calcium has always been low for some reason. When the tub was new I used to add calcium increaser but I don't hassle with it anymore. Any huge concerns if my calcium is always under 100?

Unless your Calcium is really low <50 and/or you also have a low pH (<7.2), I wouldn't worry about it. If you keep your pH in the 7.4-7.8 range you're fine.

[Hillbilly Hot Tub]

Di chlor is close to netural at 6.8 and bleach (sodium hypochlorite) has a very high PH of 13 so its all ready an issue. Where are you getting that bleach is PH netural?

[Vinny]

The reaction of chlorine when its doing its job is an acidic reaction. If you add enough dichlor to do the job (3 PPM) and enough bleach to do the job (3 PPM) the overall effect for dichlor is to become acidic where the bleach becomes PH neutral.

Initially what you said is true but after the reaction things change.

[Nitro]

What Vinny said is correct.

[Vinny]

Just a follow up on the PH vs alkalinity and using baking soda.

I added 2 oz of baking soda to my tub Friday night and the PH went to 7.8 and alkalinity went to 110, originally the PH was 7.4 and the alkalinity was 80. I measured these today.

Other than jets without air running to mix the baking soda in the water and some dichlor to sanitize the water nothing else has been added.

[Nitro]

Vinny,

FYI, pH rise doesn't necessarily require physical aeration. Just having the water exposed to air can still allow outgassing, though not as much as injecting air. The pH would rise to 7.8 if only 5.4% of the carbonate in the water were outgassed. Two days could have be enough time for that to happen.

2 oz of Baking Soda would raise your pH from 7.4 to 7.5, with no outgassing (assuming 350 Gal tub). So the rise from 7.5 to 7.8 was from outgassing.

[Vinny]

But it doesn't affect pool water and why?

It would seem that whatever a tub's water does would be what a pool's water does. I understand the volume difference but you would be adding the same proportionate amount of baking soda, chlorine or whatever to a pool as you would to a spa.

I just doesn't make sense to me that a spa's water is that much different than a pool. I can see if air is injected but other than a little splashing from the neck jets there is no air injected.

Also I don't have any covers on the pool during the summer and it has all the time to out gas. For some reason I have a hard time believing that spa water behaves that much differently than pool water with PH & alkalinity and it has to do with simple out gassing.

Can you explain why 400 gallons is affected by 2oz and 13,000 gallons is not when I raise the alkalinity from 80 to 110 or 120 in the pool. I would imagine I would be using approx 32 times more baking soda (13000/400 = 32.5) which would equal 64 oz.

[Nitro]

Can you explain why 400 gallons is affected by 2oz and 13,000 gallons is not when I raise the alkalinity from 80 to 110 or 120 in the pool. I would imagine I would be using approx 32 times more baking soda (13000/400 = 32.5) which would equal 64 oz.

Temperature!

The water temp is the key. The rate of outgassing is also a function of temperature, with faster outgassing at higher temperatures.

If you want to see the isolated effect of adding baking soda to your hot tub, you should measure the pH after 15-30 minutes. There is no reason to wait a day or two. Acid and Base are well dispersed within 30 mins with the jets running.

I balanced my friend's hot tub water in a few hours, when his TA was over 400 ppm, and his pH was too high to measure. If you understand the point about pH rise via aeration, you can balance your water in a day, and never (or very rarely) need to add acid or base.

[Vinny]

Temperature!

The water temp is the key. The rate of outgassing is also a function of temperature, with faster outgassing at higher temperatures.

If you want to see the isolated effect of adding baking soda to your hot tub, you should measure the pH after 15-30 minutes. There is no reason to wait a day or two. Acid and Base are well dispersed within 30 mins with the jets running.

I balanced my friend's hot tub water in a few hours, when his TA was over 400 ppm, and his pH was too high to measure. If you understand the point about pH rise via aeration, you can balance your water in a day, and never (or very rarely) need to add acid or base.

The general rule of thumb here is to wait at least 4 hours (longer the better) to keep from measuring PH that is swinging vs steady PH. I will test the PH in 20 minutes next time to see if PH is lower.  Besides it was raining and I didn't want to get wet!

I thought you were going to say that temperature affects outgassing so does the effect on the cabonate in the water change over time? Such as a higher change will occur in the first 3 days vs (1,2,3, ...) week(s) later of adding baking soda if the temp rises higher.

[Nitro]

I thought you were going to say that temperature affects outgassing so does the effect on the cabonate in the water change over time? Such as a higher change will occur in the first 3 days vs (1,2,3, ...) week(s) later of adding baking soda if the temp rises higher.

The higher the pH the slower the outgassing (pH rise). Eventually it will hit an equilibrium that's dependent on your TA. This is why you should adjust TA, not pH. Your pH will fall in line if your TA is tuned. However, if you ignore TA and focus on pH, it's more difficult to keep your pH under control, without constantly adding acid or base. The only reason to add Acid or Baking Soda, should be to fine tune your TA to make your pH more stable.

Merry Christmas!