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Confusion About Lowering Ta, Can't Get Water Balanced


kincade
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I've been reading here for a while and the information is amazing! I'm hoping to solicit some of your help with a few questions I have. Please bear with me as I'm still a newbie at this!

I'm currently trying Nitro's approach to water here and I am on the 3rd day of the attempt. If I am understanding his writeup correctly he describes the way to lower TA as to aerate until the PH reaches 8.0, then pitch dry acid and lower to 7.0. Then to repeat the process until the PH stabilizes on it's own at 7.6 and the TA shouldn't go lower than 50ppm.

However, in trying this I got to 40ppm TA yesterday and the PH still rises to 8.0. Should I keep trying it until the TA reaches 0 (I was under the impression that anything below 50 is bad)? And will aerating ALWAYS bring the PH up, requiring correction after each soak, even after 'balancing' the water?

I was worried that the TA was too low, so I pitched some baking soda to raise it back up to what I think is a 'safe' level. My water currently reads as such )with the Taylor k-2006):

TA-90

CH-150

Ph-7.3

2ppm fc

Nature2 stick

0 CC

CYA < 30

50ppm borates via gentle spa (17 oz in a 420 gallon tub).

Ideally I was trying to get the CSI to 0, but I can't seem to get the TA low enough to get the PH to not rise during aeration.

Lastly, Nitro doesn't mention anything about stain and scale control, anti foam, or scum balls. But my dealer is really pushing that I should use all 3. Do any of you have any clarification on whether they should be needed?

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When the TA got to 40-50 ppm, stop adding acid, but also stop aerating when the pH gets to 7.5 or so. Are you saying that even with the TA at 40-50 ppm and with 50 ppm Borates in the water and with the spa covered and not aerating the pH still climbed to 8.0? The pH will usually rise when aerating, even at the lower pH, but just not as much (especially with the 50 ppm Borates).

I'd drop the TA to 60 ppm and start using Dichlor which is net acidic. It should help keep the pH down. After you've cumulatively added around 33 ppm FC worth of Dichlor (perhaps a week or so) then switch to using 6% regular Clorox bleach.

Does your spa have an ozonator? Perhaps that is on a lot and the bubbles are causing more aeration.

You shouldn't need stain and scale if you properly balance your water unless you have metal ions (iron, manganese) from your fill water. You shouldn't need any anti-foam if your Calcium Hardness (CH) is at least 120 ppm. You shouldn't need scum balls if you use enough chlorine every day after your soak, unless you are particularly unclean when getting in the tub (i.e. with lotions, etc.).

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When the TA got to 40-50 ppm, stop adding acid, but also stop aerating when the pH gets to 7.5 or so. Are you saying that even with the TA at 40-50 ppm and with 50 ppm Borates in the water and with the spa covered and not aerating the pH still climbed to 8.0? The pH will usually rise when aerating, even at the lower pH, but just not as much (especially with the 50 ppm Borates).

I'd drop the TA to 60 ppm and start using Dichlor which is net acidic. It should help keep the pH down. After you've cumulatively added around 33 ppm FC worth of Dichlor (perhaps a week or so) then switch to using 6% regular Clorox bleach.

Does your spa have an ozonator? Perhaps that is on a lot and the bubbles are causing more aeration.

You shouldn't need stain and scale if you properly balance your water unless you have metal ions (iron, manganese) from your fill water. You shouldn't need any anti-foam if your Calcium Hardness (CH) is at least 120 ppm. You shouldn't need scum balls if you use enough chlorine every day after your soak, unless you are particularly unclean when getting in the tub (i.e. with lotions, etc.).

Chemgeek; I had not added the borates yet (just added them last night). However, doesn't one aerate the spa every time they turn on the jets, thus raising the PH? This was my problem, that I added acid repeatedly while aerating (enough to bring it down to 7.0) and every time it raised to 8.0 while the TA dropped down below 50ppm. The way I read the procedure, when the TA reached around 50 the PH would naturally rise to 7.6 and then stop. Am I reading this wrong?

Thanks for all of the answers!

My spa does have an ozonator. It runs every 30 minutes for perhaps 1 minute, and then every 12 hours for 2 hours.

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See how things go at a TA of 40 or 50 ppm and with the 50 ppm Borates. I think you're not having the Borates made the problem worse. The Borates should cut the rate of pH rise at least in half and that might be more tolerable. Your ozonator probably isn't helping, but that's just the way it is. If after the borates you still can't maintain pH easily, then you could use Dichlor-only instead and change the water more frequently since Dichlor is net acidic -- either that or you may need to add acid more frequently. Again, see what happens after the borates as they should help. You may also do better after you get the CYA up from a week of Dichlor (CYA is another pH buffer as well).

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See how things go at a TA of 40 or 50 ppm and with the 50 ppm Borates. I think you're not having the Borates made the problem worse. The Borates should cut the rate of pH rise at least in half and that might be more tolerable. Your ozonator probably isn't helping, but that's just the way it is. If after the borates you still can't maintain pH easily, then you could use Dichlor-only instead and change the water more frequently since Dichlor is net acidic -- either that or you may need to add acid more frequently. Again, see what happens after the borates as they should help. You may also do better after you get the CYA up from a week of Dichlor (CYA is another pH buffer as well).

Is there any problem with TA 40 per se? If the TA is 40 and the CSI is near zero, is that still a problem?

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It's OK so long as you've got some kind of supplemental pH buffer in the water such as 50 ppm Borates. One can always increase the CH to keep the CSI from getting too negative.

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It's OK so long as you've got some kind of supplemental pH buffer in the water such as 50 ppm Borates. One can always increase the CH to keep the CSI from getting too negative.

Chem,

Thanks for the information and clarification. If you don't mind I'd love to ask a few more questions.

I'm still unclear on aeration... Will aeration ALWAYS cause a PH rise, even when the water is properly balanced? Or the water is balanced will PH be controlled and limited at 7.6?

Secondly, is the whole goal to reach a CSI of 0? Specifically at my current setup (7.4 ph, 70 TA, 150ch) my CSI is -.25. I can get it close to 0 by bumping the CH with calcium chloride or raising the PH to 7.6 (which doesn't seem smart, considering I couldn't get it to stay down previously).

Lastly, I've been reading up on Borates, specifically the ones in Gentle Spa. I'm a bit shocked to read about borate toxicity, especially dermal? Some of the side effects listed are liver cancer, skin irritation, etc. And it appears it can also be used as a herbicide/insecticide. On the other hand, one benefit is listed as its anti microbial properties. Am I to assume that in our concentration (50ppm) that the benefits outweigh the risks, or is the risk I've read about at all true?

Thanks again!

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If you aren't adding any other chemicals to the water that would otherwise move the pH, then pool or spa water will always tend to rise in pH with more aeration unless the TA is very low or the pH very high. This chart shows how over-carbonated pool or spa water is due to the extra carbon dioxide that is in the water due to higher TA or lower pH. The chart assumes a 30 ppm CYA level. So you can see that only when you get to a TA of 40 ppm with pH of 8.0 (or other combinations not shown on the chart) is there the natural amount of carbon dioxide in the water as there is in the air. At that point, aeration won't cause any more change in pH. In practice, anything near that point won't show much change either. As you move towards the lower-left, the rate of pH rise will increase (assuming the same amount of aeration). You don't even have to physically aerate the water either -- physical aeration just accelerates the process, but the outgassing of carbon dioxide happens anyway, albeit more slowly when the water is calm. If you cover the spa or pool then that reduces the outgassing even more.

Note that if you use some cheap "Ultra" brand of bleach, this can have a high pH of 12.5 or more and therefore have too much "excess lye" that will cause the pH to rise from continued use. The best bleach to use is 6% Clorox Regular unscented as it has a pH of 11.9 so has minimal excess lye.

At a TA of 40 ppm and a pH of 7.7, the "1.1" in the table means that there is about twice as much carbon dioxide in the water as would normally occur based on the amount in air.

As for the CSI, you can target a somewhat lower CSI since the gas heater will be hotter at its surface. Usually, targeting -0.2 is fine. You don't have to be precise about this. If you get above 0, then you can start risking scaling though even then it usually doesn't happen unless it gets quite a bit above zero, though in spas it seems to be seen at around +0.3 as opposed to needing to be at +0.7 or higher for pools.

As for borates, concentration is everything. Too much ingestion of salt can kill you as well, which is why you can't just drink saltwater from the ocean at sea and expect to survive. Your body is able to eliminate borates -- they do not bioaccumulate -- but your liver can only eliminate it so fast. At the level in spas and pools, it's fine so long as you don't regularly drink the water -- something you normally would not do. If one has dogs that drink from pools regularly, then having borates wouldn't be good though one should really just train their dog to drink from a bowl. More info on borates toxicity is in this post I wrote.

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Thank you for all of the helpful information!

As of 2 days ago I thought that I was starting to wrap my head around this. But my chlorine usage seems to be abnormally low from soaking. All of my after soak adds have been much lower than the required amount. My water was staying pretty steady at ph 7.5, TA 60, CH 150, CYA of around 20 (taylor test totally full and cloudy but can see dot through the solution still). Borates have been added at 50 ppm.

THEN we had a hot tub party on Saturday night. FC before was 1.0, and we had 5 person hours of soaking. Afterwards, I added 7tsp of Dichlor (less than 1/2 the suggested amount). Next day at 130pm FC was 6.5, and even at 930 it was 5. PH was 7.3 I soaked for 30 minutes last night without adding anything. And this morning, Ph is 6.8!

Any idea what I've done? I'm on my way to the spa store to buy some Ph up as I didn't think I'd need to worry about the PH dropping!

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I don't think that pH up is the best choice. If the pH is dropping, then you should probably add baking soda to raise the TA, which will raise the pH.

If you used boric acid to add 50 ppm borates, then that would lower the pH somewhat.

Dichlor is somewhat acidic and requires a higher TA than when you're using regular, unscented 6 % bleach.

During the dichlor phase, you will want a TA of around 80. When you switch to bleach, you will want a TA closer to 60 ppm.

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I don't think that pH up is the best choice. If the pH is dropping, then you should probably add baking soda to raise the TA, which will raise the pH.

If you used boric acid to add 50 ppm borates, then that would lower the pH somewhat.

Dichlor is somewhat acidic and requires a higher TA than when you're using regular, unscented 6 % bleach.

During the dichlor phase, you will want a TA of around 80. When you switch to bleach, you will want a TA closer to 60 ppm.

Thanks for the response Quantum!

I added Gentle Spa to get the 50ppm (16 oz IIRC) needed, and it immediately pushed the Ph to around 8.0. This was approximately a week ago.

I didn't know that the TA should be a different level during the Dichlor phase; I'll add some baking soda tonight and see if I can get the PH to come back up. If it doesn't come on it's own, am I safe to add PH up?

My CH is around 150, and according to the pool calculator I'm currently sitting around -.5. If I bump the CH to 200 it would help with that, but I hesitate to do that until i get the PH under control.

Also, do you think my after soak usage seems very low? I'm adding less than 1/2 recommended, and the FC the next day is still too high! Is my ozonator working THAT well?

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I'll add some baking soda tonight and see if I can get the PH to come back up. If it doesn't come on it's own, am I safe to add PH up?

You can use pH up if you want. I almost never use it. I find that when the TA is right, the pH will fall right in line.

Before adding pH up, you should try aerating the water to raise the pH.

My CH is around 150, and according to the pool calculator I'm currently sitting around -.5.

What numbers are you using to get -0.5? I think that you're higher than that. What temperature are you using?

If I bump the CH to 200 it would help with that, but I hesitate to do that until i get the PH under control.

I wouldn't increase the calcium at all. 150 ppm is plenty. You want to maintain a slightly negative CSI. I recommend around -0.15 to -0.10. I would use a higher pH rather than a higher Calcium level to raise the CSI, if necessary. I usually use a pH of 7.8.

Also, do you think my after soak usage seems very low? I'm adding less than 1/2 recommended, and the FC the next day is still too high! Is my ozonator working THAT well?

Trust your numbers. The rule of thumb is just a starting guideline. A good ozonator can take care of a substantial amount of the oxidizer demand.

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