Is Ta Of 40 Too Low?

[flyguyscott]

I have an Arctic Spa with the Onzen Salt System using a Sodium Bromide salt. I'm not using the Aquafiness the dealer supplied on delivery of the spa.

All is generally well, but as I was informed, the pH naturally drifts high with a salt water system and I have certiainly been experiencing this at all TA levels.

It seems to be a chore to balance the pH and TA with such a drift. I contunuously have to add the "Adjust Down" which reduces pH as well as TA and then add the "Perfect Balance" which increases TA with a small increase in pH. Doing this a couple times a week I seem to be going through more chemicals than I think I should.

My TA doesn't ever seem to go below 40, so if it's held at that level, I seem to be able to add the "Adjust Down" to get the pH down a bit and keep the TA where it is.

If I keep the pH a little higher around 7.6 - 8.0 then thepoolcalculator.com says that my water is balanced. The only issues is that with a higher pH Bromine seems harder to produce.

Is a TA of 40 too low? If so what problems will it cause? Should I use something with Borates to help stabalize the pH in a salt system? I have about $200 worth of Aqua Finesse the dealer gave me with installation of the Spa. It's suppose to lock in the pH but also contains it's own salts and other biofilm agents so it could have other effects on the water.

Should I try the opposite and get a high TA (Arctic documentation reccomends keeping it high around 125 to 150) which should help stabalize the pH so I don't have to adjust it as much but I'll still have to go through the 2 step process every time I need to balance the water. I suppose this is more ideal because I can keep the pH low which seems to help with bromine.

What are your thoughts?

[quantumchromodynamics]

40 is not too low. You should keep the alkalinity where it maintains a stable pH. A high alkalinity will not work. It will cause your pH to rise.

You should not be adding the SpaGuard Perfect Balance with a Salt System. SpaGuard Perfect Balance is a phosphate based pH balancer. Most salt system manufacturers do not want phosphates in the water.

Adding 50 ppm borates from Borax or boric acid will help stabilize your pH. I recommend that you use the

boric acid instead of the Borax.

[chem geek]

(wrote this as QCD posted; duplicate info here)

If you raise the TA higher, you'll only make the problem worse. Having the TA be low and using 50 ppm Borates is probably the better combination and also don't target a low pH -- 7.7 of 7.8 is OK for example. However, since the TA isn't having a big effect on your pH stability, I suspect that your SWG is outgassing chlorine gas as well, not having it dissolve in the water completely before outgassing. That would be similar to adding lye to the water which would raise the pH and TA while adding acid would lower the pH and TA back down. So near 40 ppm TA this may be what is happening -- that is, your TA isn't dropping as much when you add the acid, but the pH still swings up.

Unfortunately, I don't know what to suggest to improve this unless you can direct your return to have the SWG bubbles mix longer with the spa water -- most of the bubbles are hydrogen gas. If you smell near where the bubbles reach the surface, does it smell like chlorine stronger than when the SWG is off?

[OttawaGreg]

Adding 50 ppm borates from Borax or boric acid will help stabilize your pH. I recommend that you use the boric acid instead of the Borax.

Any particular reason you recommend Boric acid over BORAX? I've been using BORAX powder and find it works great.

thanks,

Greg

[flyguyscott]

You should not be adding the SpaGuard Perfect Balance with a Salt System. SpaGuard Perfect Balance is a phosphate based pH balancer. Most salt system manufacturers do not want phosphates in the water.

I'm using Actic's Perfect Balance to increase the TA. It has small tendance to increase pH when added. I'm not sure if it's similar or different from SpaGuard's product. I couldn't tell you what it's made of as it doesn't say anything about it's contents on the package.

I can only assume that it shouldn't cause problems as this is the specific product they gave me to increase TA.

[quantumchromodynamics]

OK, thanks for the clarification. I found an MSDS that says that it is sodium bicarbonate. I should have checked with you before I assumed that it was SpaGuard. Sorry for the confusion.

[quantumchromodynamics]

Any particular reason you recommend Boric acid over BORAX? I've been using BORAX powder and find it works great.

thanks,

Greg

Borax is fine to use. I did not mean to imply that it was not good to use.

My primary reason to prefer boric acid over the Borax is because the water will contain both borate and boric acid. The percentage of each will depend on the pH of the water. Here are some values for boric acid and borate based on the pH.

pH = 8.3 Boric acid = 91 % Borate ion = 9 %.

pH = 8.2 Boric acid = 93 % Borate ion = 7 %.

pH = 8.1 Boric acid = 94 % Borate ion = 6 %.

pH = 8.0 Boric acid = 95 % Borate ion = 5 %.

pH = 7.9 Boric acid = 96 % Borate ion = 4 %.

pH = 7.8 Boric acid = 97 % Borate ion = 3 %.

pH = 7.7 Boric acid = 97.5 % Borate ion = 2.5 %.

pH = 7.6 Boric acid = 98 % Borate ion = 2 %.

pH = 7.5 Boric acid = 98.4 % Borate ion = 1.6 %.

As you can see, most of the "Borates" will be in the form of boric acid at normal spa pH.

This makes using the boric acid more pH neutral than using the Borax. Using the Borax requires the addition of muriatic acid to convert the borate ions into boric acid.

Using pure boric acid requires little or no additional chemicals except for perhaps a little pH increaser to convert some of the boric acid into borate ions.

[OttawaGreg]

Any particular reason you recommend Boric acid over BORAX? I've been using BORAX powder and find it works great.

thanks,

Greg

Borax is fine to use. I did not mean to imply that it was not good to use.

My primary reason to prefer boric acid over the Borax is because the water will contain both borate and boric acid. The percentage of each will depend on the pH of the water. Here are some values for boric acid and borate based on the pH.

pH = 8.3 Boric acid = 91 % Borate ion = 9 %.

pH = 8.2 Boric acid = 93 % Borate ion = 7 %.

pH = 8.1 Boric acid = 94 % Borate ion = 6 %.

pH = 8.0 Boric acid = 95 % Borate ion = 5 %.

pH = 7.9 Boric acid = 96 % Borate ion = 4 %.

pH = 7.8 Boric acid = 97 % Borate ion = 3 %.

pH = 7.7 Boric acid = 97.5 % Borate ion = 2.5 %.

pH = 7.6 Boric acid = 98 % Borate ion = 2 %.

pH = 7.5 Boric acid = 98.4 % Borate ion = 1.6 %.

As you can see, most of the "Borates" will be in the form of boric acid at normal spa pH.

This makes using the boric acid more pH neutral than using the Borax. Using the Borax requires the addition of muriatic acid to convert the borate ions into boric acid.

Using pure boric acid requires little or no additional chemicals except for perhaps a little pH increaser to convert some of the boric acid into borate ions.

Thanks for that explanation, great. I use BORAX to raise my pH as well so I'm not really looking to be pH neutral.

Greg

[chem geek]

I just want to make it clear that though having 50 ppm Borates in the water slows the rate of pH rise roughly in half, it does not by itself reduce the amount of acid you need to add. So when the pH rises to the same point as before adding Borates, you'll have to add twice as much acid to bring the pH back down. The only way to reduce the amount of acid you need to add is to lower the TA which reduces a key source of rising pH in the first place. And as was mentioned, using a bleach, such as Clorox Regular 6% unscented, will be better than off-brand bleaches that often have way too much excess lye in them, so it's like adding Spa Up along with the bleach in that case -- not something you want to do.

Many off-brand Ultra bleaches are 6% chlorine, but have a pH of around 12.5 and have around 0.25% excess lye (sodium hydroxide) in them. If you added 4 ppm FC of this bleach per day (that got used up at that rate per day), for example, then the excess lye (with no borates and a TA of 60 ppm) would result in a pH rise of around 0.16 per week. Any additional pH rise is most likely due to a high TA (and aeration) which results in more carbon dioxide outgassing.