Getting started on borate

SteelBlue

Well-known member
Jul 4, 2019
81
Scottsdale, AZ
I have a 20,000 gallon negative edge pool that is low on TA (~60) and taking daily acid. I figured this would be an ideal situation to begin borates. I dumped in the whole 55 lb can of boric acid obtained via Duda. Beginning pH was 7.4 and it did not change after the addition. Resulting borate level was 30 ppm per the LaMotte test strip. FC is 3 ppm and I'm using the Triclor tabs to chlorinate until my non-existent CYA levels are built up. I'll then switch to liquid chlorine. Visually the pool is the same, haven't gone swimming in it yet to test the "feel." I'm hoping the borate addition may also help reduce the honey bees that plague me every year. I also must say that the 55 lb boric acid bucket, now empty, makes a very nice trash can. I'm wondering if I should order another bucket and increase my borates to 50 ppm.
 

JamesW

TFP Expert
Mar 2, 2011
17,289
I would hold off on more borates. If you increase the cyanuric acid level, it has a similar effect as adding borates. Also, maintaining the pH at 7.8 will help. Keep the CSI between -0.3 and 0.0.
 

JamesW

TFP Expert
Mar 2, 2011
17,289
CYA is a pH buffer like bicarbonate and borate.

Total alkalinity is really a measure of pH resistance to pH drop.

Total Acidity is a measure of pH resistance to increase.

Carbonic acid, boric acid, cyanuric acid and bicarbonate make up total acidity.

Carbonate, borate, cyanurate and bicarbonate make up total alkalinity.
 

JamesW

TFP Expert
Mar 2, 2011
17,289
The need for a pH buffer is mostly misunderstood. Pools really don't need much buffering.

Buffering is only necessary if random amounts of acids or bases were being added to the water at random times for no reason. That should not be happening.

By far, the primary cause of pH rise is too much carbon dioxide. Carbon dioxide is created by carbonate alkalinity and low pH.

It might seem like a higher TA would give you more pH buffering, but it actually makes the pH rise faster due to the amount of carbon dioxide that is created.

By maintaining a lower carbonate alkalinity and a higher pH, the carbon dioxide is reduced and pH rise should slow down or stop completely.

Typically a TA of 60 and a pH of 7.8 is a good choice. A CYA of 60 helps as well.

If you have a TA of 60 and a CYA of 0, the carbonate alkalinity is 60. But if the TA is 60 and the CYA is 60, the carbonate alkalinity is 40 and the cyanurate alkalinity is 20. So, a higher CYA reduces the carbonate alkalinity at the same TA.

Maintaining the CSI between -0.3 and 0.0 in plaster pools helps reduce plaster dissolving. Dissolving plaster raises the pH from the carbonates and hydroxides in the plaster.
 
  • Like
Reactions: bdavis466

SteelBlue

Well-known member
Jul 4, 2019
81
Scottsdale, AZ
I was keeping my pH slightly lower because I have some light plaster dust embedded in the darker pebble tec that I was hoping might disappear in time in a more acidic environment. Hope this is correct thinking.
 

SteelBlue

Well-known member
Jul 4, 2019
81
Scottsdale, AZ
Plugging in my current numbers, the easiest way to achieve a CSI of -0.3 would be to drop my pH to 7.2, temporarily of course and see if the plaster scale will improve.
 
Last edited:

JamesW

TFP Expert
Mar 2, 2011
17,289
How bad is the plaster dust?
Are you sure that it's plaster dust?
Did you brush daily for the first 30 days?
Did you maintain the correct chemistry during startup?
 

frogabog

Gold Supporter
LifeTime Supporter
Jul 16, 2010
2,833
Portland, Oregon
I would go to 7.4. The TA will drop some at a pH of 7.4 and that will lower the CSI enough.
Could I semi hijack this, and point you to my conundrum?

My TA has been slowly decreasing while the pH also decreases in greater amounts. We have refilled a little though so I figured that was some of it. I'm interested in your takeaway on my decreasing pH issue vs TA. TY
 

SteelBlue

Well-known member
Jul 4, 2019
81
Scottsdale, AZ
I personally did not maintain it for the first 30 days, the installer did. And it was not brushed daily.

Since I’ve added boric acid (4 days ago) I’m still needing to add daily acid (about 2 lbs dry acid per day) to keep it at pH 7.4.
 
Last edited: