Borates and SWG?

Backcountryski

Active member
Aug 31, 2019
30
WA
Noob here, I have a hot tub coming in a couple of weeks and have been reading as much as I can prior to it's arrival. Regarding Borates in your water, I have seen mention several times that they are somehow beneficial to your SWG system, or that they make it more efficient. Can someone here explain a little more? I spec'd the hot tub to come with SWG, and if borates will make it more efficent or somehow more reliable I am game.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,451
Laughlin, NV

Take a look at the above article.

Borates will not make your SWCG more efficient. They reduce pH swings which can be useful.
 

Backcountryski

Active member
Aug 31, 2019
30
WA

Take a look at the above article.

Borates will not make your SWCG more efficient. They reduce pH swings which can be useful.
Thanks for the reply, I have read the article, several times. Here is just one of the comments that I have come across that I was referencing "Borates in my pool water has been a net positive for me. Better pH control (let's me run my TA on the low side) and I got a little efficiency boost in sanitizing as the SWG could run a little easier". I have seen several other comments such as this, which was what lead to my question.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
15,894
Tucson, AZ
Borates can act as a mild algaecide and so people usually see that “boost” in efficiency because borates can make it harder for algae to replicate. Borates also strongly buffer against high pH changes inside the cell as the pKa is around 9.0 for the boric acid/borate ion buffer system. Keeping the pH in check means that calcium scaling is less likely and thus the cell can run without getting coated with scale. Scale reduces the efficiency of the cell.
 

Backcountryski

Active member
Aug 31, 2019
30
WA
Borates can act as a mild algaecide and so people usually see that “boost” in efficiency because borates can make it harder for algae to replicate. Borates also strongly buffer against high pH changes inside the cell as the pKa is around 9.0 for the boric acid/borate ion buffer system. Keeping the pH in check means that calcium scaling is less likely and thus the cell can run without getting coated with scale. Scale reduces the efficiency of the cell.
Thank you, exactly what I was looking for! So if I follow the logic, the borates help kill any algae, thus reducing how much chlorine is burned up to kill any algae, thus you can run the SWG at a lower setting and theoretically maintain same level of chlorine? I am in. My tub will be 330 gallons, pool math tells me I need roughly 8 oz boric acid (to get to 30 ppm). I looked on the suggested websites and it appears relatively cheap, even with water changes every few months. I believe I am sold....
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
10,800
Northern NJ
Thank you, exactly what I was looking for! So if I follow the logic, the borates help kill any algae, thus reducing how much chlorine is burned up to kill any algae, thus you can run the SWG at a lower setting and theoretically maintain same level of chlorine?
Don’t focus on the comment thar Borates is a mild algaecide. You need to maintain recommended FC levels for sanitation.

While Borates tend to have a minimal effect as an algaecide one shouldn’t utilize them to prevent algae. The boron concentration that that is required to noticeably reduce the risk of algae is far higher than what is generally considered safe so we generally don’t utilize them to prevent algae, we only focus on the benefits for buffering pH changes.
 

Backcountryski

Active member
Aug 31, 2019
30
WA
Don’t focus on the comment thar Borates is a mild algaecide. You need to maintain recommend FC levels for sanitation.

While Borates tend to have a minimal effect as an algaecide one shouldn’t utilize them to prevent algae. The boron concentration that that is required to noticeably reduce the risk of algae is far higher than what is generally considered safe so we generally don’t utilize them to prevent algae, we only focus on the benefits for buffering pH changes.
I'm tracking with you. Don't worry, I plan on maintaining FC religiously. The thread was more of a curiosity, wanting to understand sort of thing.
 

AUSpool

Bronze Supporter
LifeTime Supporter
TFP Guide
Sep 23, 2015
668
Brisbane, Australia.
... My tub will be 330 gallons, pool math tells me I need roughly 8 oz boric acid (to get to 30 ppm)...
I would start at 50ppm. You can get the borate test strips from TFTestKits. Test strips or guess strips as their sometimes referred as are not the best test method but for borate they are close enough. Start at 50ppm, when you get to 30ppm add enough to get back to 50ppm. With splash out and water changes your borate concentration will roughly trend the same as your salt and/or CH.