pH Adjustment Frequency before and after borates

[kwhoward]

Hello all... new to forum and this is my first post.

I have read all that I can find regarding adding borate to a pool and am considering adding to my pool, but would like an answer to some questions first. I have an ~15,500 gallon pool (about 5 months old) with a SWG. My CYA is at 40, TA is at 90, FC is at 4 and stable, CH is at 260, and my salt is at 3600 according to the generator, but the test strips say it's 2800. I am finding that my pH is at 8.0 about every three days and the acid demand test tends to take 1 drop indicating I need a pint of acid according to the Pool Calculator, which is correct because pH is at 7.6 the next day. If I wait 5-6 days it takes two drops and a few ounces shy of a quart to get the pH to 7.6. Now I understand that the SWG is the likely culprit for the rising pH plus some aeration from spa overflow.

So, my question is... will adding borate to 40 ppm quantitatively extend the time required before pH rises out of range? If yes, has anyone actually observed the difference? How many days before and after for comparison? If yes, does this increased time actually offset acid use over the same defined time period? I ask the last question because I see the presence of the borate will require much more acid to effect the same reduction in pH due to it's buffering ability. According to the Pool Calculator it would take 16 oz to go from 8.0 to 7.6 without any borate in the pool and 49 oz with borate at 40ppm. That's triple the amount of acid! In the end, are you really saving any acid (aka money) or are just adding more acid far less frequently and consuming the same amount. In my situation, I'll add 48 oz over nine days, or 16 oz every three days. Will borate just make that roughly 49 oz every nine days or even longer?

If borate maintains desired pH for a sufficiently longer time period than no borate, then that's less testing and less frequent addition of acid, which is a good thing in my book.

I eagerly await responses.

Thanks, Ken

Free form plaster pool and spa with three overflows
~15500 gallons
(Jandy) Stealth Pro 2-speed pump, DEV DE filter, JXi Heater, AquaPure SWG

 

[pooldv]

Welcome to TFP!

Good job reading up! The first thing to do is lower your TA to 60 and see how your PH does and see if it will stay at 7.8 for a week or two. If not, then lower it to 50 and try again. Often PH will stabilize at 7.8 with TA at 50-60. We have several contributing members with TA at 50 this year and PH much more stable, including me. Then you can add borates and never or rarely add acid.

 

[kwhoward]

Welcome to TFP!

Good job reading up! The first thing to do is lower your TA to 60 and see how your PH does and see if it will stay at 7.8 for a week or two. If not, then lower it to 50 and try again. Often PH will stabilize at 7.8 with TA at 50-60. We have several contributing members with TA at 50 this year and PH much more stable, including me. Then you can add borates and never or rarely add acid.

Thanks so much. I was following the recommendations for TA on the Pool Calculator with the Trouble Free Pool setting, which suggest TA = 60-80. I checked last night and it is at 80, so I'll push pH down to 7.2 and aerate with the water fall to drop TA to at least 60. I like the idea of rarely adding acid. I played around on the calculator and determined that with borates at 40 ppm then 3 times the acid is required to effect the same pH change that without borates. That's some serious buffering and jives with the idea that pH should be very stable with borates. FYI to anyone that hasn't checked recently, the Granular Boric Acid from Duda Diesel in the 55# bucket is only $63.95 with about $29 shipping. I think that's less than some prices I saw referenced in older posts.

 

[mikemass]

Great thread, Great questions and EXCELLENT research before posting. Definitely subscribing for more information as I am curious to the quantitative effect of Borates as well.

 

[kwhoward]

OK, months later... Now I really have a "problem" I can't figure out. I added borates, but the results are less than desirable and I really hope someone can solve this.

First let me give my chemistry before adding borates. pH 7.6, TA 70, CA 80, Salt 3200, CH 325, FC 4 CC 0. A note on TA... I cannot get it lower than 70 because my fill water is 70. I can get it to 60 but it comes right back up to 70 in a few days. A note on pH... I was having to add acid (liquid) about every 2-3 days to keep my pH below 8.2 to 8.4. I noticed that when I tested with my Taylor kit that the addition of one drop of demand reagent dropped the pH color precisely 0.4 (This is relevant later). This was useful to tell when my pH had actually gone up to 8.4, e.g. 2 drops would change the color to 7.6. The amount of acid added without borates was maybe 19 oz or so to drop from 8.2 to say 7.6 per the Pool Calculator and this drop could be verified accurate a couple hours later. Then 3 or less days later pH would be back at 8.2 so my daily rise was around 0.2. The moral of this story is that based on my pool size, I always get he expected result when adding chemicals. It's not like I add 19 ounces of acid and my pH drops to 7.0 if you get my point (again, this becomes relevant soon).

I used the pool calculator to determine the amount of Borax and acid to add with a starting pH of 7.6 (777 oz of Borax). I added exactly per the instructions testing pH after adding the first half and "stirring" and again after adding the second half and "stirring". Both times my pH was at 7.6... kind of cool and a validation of the calculator. I ran my pump per instructions and tested the borate level with the LaMotte strips after about three days. The strips put the level between 30 and 50 with the color very close to 50. I added enough borates to get my level to 40, so right on the money I'd say. I did confirm a TA rise from 70 to 90 after adding the borates, but it is now down to 80. Everything should be rainbows and unicorns now, right? pH should stabilize more so than prior to the borates, which is the whole point of adding them to a SWG pool, right?

So now for the the problem.... My pH is going up just as fast to about 8.2 (tough to tell since the test maxes at 8.0 but the color is definitely darker than 8.0) Of course now I have to use way more acid to effect the same pH change, or at least one would think. I followed the calculator for my new chemistry (same as above except Borates at 40 and TA at 80). The calculator said to add 74 oz acid to go from 8.2 to 7.7. I added it and tested pH about 3 hours later (pump running on high). It was at 7.4. I have confirmed this twice when adding acid. I also notice it takes slightly more than twice as much demand reagent to change the test color. According to the calculator I would have had to add about 98 oz of acid to drop from 8.2 to 7.4. Alternatively I played with the calculator and if my borate level was really at 25, then adding 74 oz of acid would have produced the result I got (pH 7.4). According to the calculator, adding 777 oz of Borax would put a 16,500 gallon pool at a borate level of 40. That is how much I added and the test strips show about 40.

In short, my pool behaves like the borate level is 25 and not 40. I'm highly confident it is at 40. In order to be wrong my pool size would have to be off by about 10,000 gallons, e.g. 26,500 not 16,500. That's just not possible! My prior chemical history clearly demonstrates a pool size of 16,500. I have low calcium content in my fill water so adding calcium chloride per the calculator produced a nearly exact rise in the calcium hardness level back when I added it. The same is true for salt, acid, or CA addition. If I add what the calculator says then I always get the expected result. Sorry for belaboring this point. As of now I have to cheat the calculator by setting the borate level to 25 in order to add the correct amount of acid for a predictable pH drop only to have to rinse and repeat three days later. Obviously this is less then desirable since I now have to use more acid and the frequency is the same. In short, adding borates just upped my acid cost significantly. It appears they are having zero effect on maintaining pH.

I will add the the water does feel much different... it's "softer" and this is not subjective... everyone can feel it. The surface tension of the water also now looks "different" (tough to explain) and though my pool was super clear it is now near see through when the water is still. At night with the pool light on it looks empty until you focus on the waterline.

If anyone can help me solve this it would be much appreciated. I'm lost. Is it the "high" TA of 80 causing this? If yes then lowering it will be expensive and even then it's nearly impossible to get it below 70.

Thanks in advance,

Ken


Free form plaster pool and 7' spa with three overflows
16500 gallons (was wrong... previously listed at 15,500)
(Jandy) Stealth Pro 2-speed pump, DEV DE filter, JXi Heater, AquaPure SWG

 

[JoyfulNoise]

Ken,

If you look at the Pool Math page, you will find this warning in the pH section -

Note: pH calculations depend on TA and Borate. Results are approximate and can be off significantly for large pH changes. Changing your pH will also change your TA.

I would say this - you are trying to make too large of an adjustment in pH using the static values in PoolMath. If you add 74 oz of MA to your pool, you will reduce your TA by almost 20ppm. So, you're assuming your TA is 80ppm when, in actuality, it is decreasing as you are adding acid. This is one of the limitations of PoolMath, i.e., you can't use it to make large adjustments. pH calculations in a solution with multiple buffers (carbonate, cyanurate and borate) is an extremely difficult calculation to make and requires iterative computation to do it. PoolMath is not that advanced.

Here's what I suggest you try - get your TA lowered back down to 70ppm (it won't take as much acid as you think it will) and the try to measure your pH and TA daily and make small adjustments - bring the pH down to 7.6 and then lower it again when it hits 7.8. I bet you will find PoolMath's numbers to be closer to the mark.

Report back and let us know how it goes.

Also, your situation is not unique - some people have added borates and have seen no effect on pH rise. It happens and it's likely a consequence of other factors that are outside their control (e.g., high TA or pH fill water, new plaster, etc). Also, 40ppm borates is on the edge of being a noticeable buffer. I know in my own pool that when my borates are below 40ppm, I can see less buffering in the pH. I always shoot to have my borates around 52-56ppm when I start the season (I lose about 6-8ppm per year) and that is sufficient to act as a decent buffer.

One more note - in the future, use boric acid to add borates to your water, it is MUCH EASIER than borax/MA.

 

[camueller]

Maybe I'm mistaken, but it seems that you think you have to replace water to lower the TA. My fill water has a TA of 250ppm, but my pool currently sits at 70 with 55ppm borates. I got there by raising my ph with aeration then knocking it back down with acid and repeating that cycle until I got my TA where I wanted it. If I recall correctly I actually had my TA at 50ppm before I added borates. Then over winter and adding water back to the pool with my hose, my TA is back up to 70. My pH never moves, always at 7.6, except for when the water gets really cold in the winter.

 

[kwhoward]

Thank you both for your responses. For camueller, I do know how to lower TA and replacing water isn't it. Sorry if it sounded that way. Also, wow, I thought my fill water TA was a bit high!!! Out of curiosity, how long did it take you to get to a TA of 70? However, you and JoyfulNoise both give me very important information. First, I need to run outside and check my TA right now to see where it's at, especially after my two acid additions that knocked pH down to 7.4. I suspect and hope that it has dropped to at least 70, though lower would be better. OK, ran and checked. It's at around 85 of so. Turns almost red at 8th drop and 9th drop turns all the way deep red. I seem to have a very hard time reducing TA. I've tried to get it below 70 by reducing pH to 7.2 and aerating, but it never gets any lower than 70 and seems to creep back up to 80 all on it's own. You make anything of that?

Both of you maintain borate levels at about 50 ppm. I guess I need to add a bit more to go up from 40 to 50. FYI, the pH of my fill water is 7.6. I'm in CA so I don't think I have to worry about my pool ever getting IL cold . I'd really love to see my pH stabilize at 7.6 or 7.7. If it did, my pool would be nearly zero trouble. I'd be left with skimming and turning the vacuum on once or twice a week.

Thank you again for the quick responses.

Ken

 

[Naplespool]

I have a new pool and have the same results as you. Pool Math is calculating how much MA is needed to combat rising PH but it takes more MA than before 50 ppm borates. Also, I've used the MA procedure to drop TA but it seems to magically bounce back from 50/69 to 70/80 over time. I am only adding MA and FC by SWCG.

 

[YetiAsr]

I have a new pool and have the same results as you. Pool Math is calculating how much MA is needed to combat rising PH but it takes more MA than before 50 ppm borates. Also, I've used the MA procedure to drop TA but it seems to magically bounce back from 50/69 to 70/80 over time. I am only adding MA and FC by SWCG.

I have the exact results as Naples as well, I'm assuming the new plaster is driving my PH up as well as SWCG ,about .1 a day it seems, my TA is increased due to the high TA in my fill water. I hope my PH stabilizes once the plaster cures, currently not super worried about it considering some of our members pool problems.

 

[kwhoward]

So Yeti and Naples are in the same situation as me. I'm not sure how new your pools are, but mine is 14 months old now. I'd think the plaster is done curing. My SWG is only running at 30% for 8 hours on low speed, so it's not like it's generating that long. It's keeping Chlorine at 4-5 ppm. You both are at 50 ppm borates and Yeti's is rising about .1 per day. I'd say my rise is about the same with 40 ppm borates and it was about .2 per day before borates. Of course now it takes way more acid to drop the pH. At this point I declare borates a horrible idea given my results. I could drop pH a lot with 20 ounces of MA and now that amount won't drop pH a measurable amount. I think that raising my borate level further (to 50+ ppm) will only result in even greater MA usage. I don't think draining my pool is viable in Southern California right now so I'm just going to have to suck up the significantly increased MA cost. Chlorine is cheap so I might try to shut down my SWG for a while to see if pH will stabilize. Any other suggestions?

P.S. Yeti, I see the same thing with TA...drop it and it magically goes back up.

 

[AUSpool]

Hey Ken,

I'm at a loss to why your pool is using using so much MA, and your pH rises so high so quickly. My pool's pH tops out at 7.8. It's gotten a little cold here and my pool has been neglected, my borates were at ~36ppm, TA at 120ppm, CYA at 60ppm and yet my pH was still at 7.8 after a few weeks of no intervention. After a big dose of MA, enough to drop my pH to 7.0 and lower my TA, the very next day it was back at 7.8.

Is it possible that it could be a pH test error, bad reagent maybe. Is your FC at or above 10ppm?

 

[NeedMoreSun]

I'm lucky, my fill water has a TA of only 60, so I actually fight to keep it at 50 in the pool with so much annual rain actually being my primary source. Mine is also vinyl. With no pets using it as a drinking source I also start each season with borates at 60 ppm. Combined with a TA of 50-60(tops) my Ph usually settles in around 7.4-7.5 and never drifts, even with the SWG. I'll see a slight rise if running a sprinkler for the grandkids, then it drops back.

Joyfulnoise and Pooldv helped me a BUNCH when first getting started, and each pool is different. However, due to prior pool maintenance company I had a sky high TA and found I made much quicker progress driving that down first, as opposed to small incremental attempts to reduce the equally high Ph.

LOL, if my pool was plaster it would melt into a glob of goo though.

 

[YetiAsr]

So Yeti and Naples are in the same situation as me. I'm not sure how new your pools are, but mine is 14 months old now. I'd think the plaster is done curing. My SWG is only running at 30% for 8 hours on low speed, so it's not like it's generating that long. It's keeping Chlorine at 4-5 ppm. You both are at 50 ppm borates and Yeti's is rising about .1 per day. I'd say my rise is about the same with 40 ppm borates and it was about .2 per day before borates. Of course now it takes way more acid to drop the pH. At this point I declare borates a horrible idea given my results. I could drop pH a lot with 20 ounces of MA and now that amount won't drop pH a measurable amount. I think that raising my borate level further (to 50+ ppm) will only result in even greater MA usage. I don't think draining my pool is viable in Southern California right now so I'm just going to have to suck up the significantly increased MA cost. Chlorine is cheap so I might try to shut down my SWG for a while to see if pH will stabilize. Any other suggestions?

P.S. Yeti, I see the same thing with TA...drop it and it magically goes back up.

If you don't mind post the results once you turn off your SWCG. Looking at my graph my PH definitely starts to fluctuate once I turned on my generator, but I also adjusted my pools chemistry for the SWG, so I'm torn on it being my adjustments or the SWG. If if it the generator driving up my PH I'm assuming once my plaster gets some age it will become stable, if it does not there is no way I'm turning it off, love it too much

 

[kwhoward]

I sure will Yeti. I'm mainly turning off the SWG to see how much of an impact it has on pH versus what is now an unknown ( 14 month old plaster?). I haven't turned it off yet, but I will tomorrow morning before the pump kicks on. I will check and adjust my pH to 7.7 at the same time and see where it goes from there. I hear you on loving the SWG... only adding acid is nice... I just wish it was far less frequent.

Steve, FC as of a couple of days ago was 7.5, so the SWG was turned down from 40% to 20% to let it fall back to 4-5 or so. As I said, I'll turn it off tomorrow. I use a Taylor K-2006 kit and recently got new Taylor R-0004 reagent (ran out). I used it prior to adding borates and it worked the same as the original reagent. I had read that borates can make chlorine generation with a SWG more efficient. I'm starting to believe it's true. The days have been getting longer and we've had warm weather with a lot of sun in Southern California. I was slowly having to turn the SWG up to maintain 4-5 ppm and now I'm having to turn it back down despite even more sun and even warmer temps after adding borates.

We have a couple of very nice lab grade pH meters at work so I'll test a sample and bring the same water into work for comparison to the meter just to be on the safe side. I have also used my original test kit and tested pH. It gives the same result as the Taylor kit.

I'll just have patience and start troubleshooting with the SWG off. Wouldn't it be fascinating if I turn it off and the pH rise persists at nearly the same rate?

This is a great discussion by the way... I love to solve problems.

P.S. I thought of something else to add... I'm not doing anything to cause aeration. My spa overflow is just from minimal cross bleed valve opening and makes no bubbles. The only bubbles I ever see is when the SWG is on and they are coming out of one of the return jets.

Thanks,


Ken
Free form plaster pool and 7' spa with three overflows
16500 gallons (was wrong... previously listed at 15,500)
(Jandy) Stealth Pro 2-speed pump, DEV DE filter, JXi Heater, AquaPure SWG

 

[JoyfulNoise]

Ken,

Can you confirm a few numbers for me as I'm having a hard time parsing the entire thread -

1. pH/TA prior to borates as well as CH;
2. pH/TA/CH of fill water;
3. plaster age and condition;
4. plaster startup process used;
5. If you have records of CH, I'd like to know what your CH rise has been over the life of the plaster;

Also, please confirm what your acid addition amounts and frequency were/are before and after adding borates.

Thanks.

- - - Updated - - -

oh, and how about your TA, where do you keep it and how quickly does it increase?

 

[kwhoward]

Ken,

Can you confirm a few numbers for me as I'm having a hard time parsing the entire thread -

1. pH/TA prior to borates as well as CH;
2. pH/TA/CH of fill water;
3. plaster age and condition;
4. plaster startup process used;
5. If you have records of CH, I'd like to know what your CH rise has been over the life of the plaster;

Also, please confirm what your acid addition amounts and frequency were/are before and after adding borates.

Thanks.

- - - Updated - - -

oh, and how about your TA, where do you keep it and how quickly does it increase?

Hi Matt,

1. pH was at 7.6 immediately before adding borates. TA was at 70. After adding borates pH was 7.6 and TA was at 90.
2. Fill water pH=7.6, TA=70, and CH=120.
3. Plaster is ~15 months old and in excellent condition, that is, white and smooth.
4. After filling with water, I brushed multiple times each day for the first 6 weeks. Then brushing was a couple of times a day for the next 2-3 weeks. Salt wasn't added for about 3 1/2 months and that was after changing the DE for the first time. The pump ran 24 hours on high for I think the first three days and then about 8 hours a day for some time thereafter.
5. I have limited records on CH, but found some in my phone's Pool Doctor app, which I started using August of last year. On 9/6/16 I adjusted CH up to 260 ppm. I was increasing incrementally so as to not overshoot. It got to 320 ppm on 9/9/16 and then on 9/12/16 it was at 370. No more Calcium Chloride was added. Maybe this is interesting... On 1/7/17 CH was at 450 ppm and then on 4/1/17 it was at 525 ppm. It seems that would take a lot of evaporation with 120 CH fill water to go up 75 ppm in 3 months. Because it was a bit too high, I drained some of the water on 4/9/17. After draining/filling, CH was at 260. I added some CC to raise it to 325 and that's where it was 4 days ago. I thought it best to leave it there and see what happens.

As for acid... before borates I was getting a daily pH rise of about 0.2, maybe a tiny bit less. The amounts of acid I added were from the pool calculator and always produced the expected pH drop. So, if I dropped it to 7.6, then about 3 days later it would be around 8.2. I'd add about 20 oz of acid to drop to 7.6. This was as consistent as the sun rising and setting and even when my SWG was running at 10%, the rise was the same. I determined the flow rate of my pump on high and low and changed to running on low for 8 hours a day for one turnover. The reason? A significant drop in my electric bill. I only run it on high to let the MX-8 cleaner run for a few hours once or twice a week. If it hits 4 hours, then I shut it off since that's slightly more than one turnover on high.

I'll use the most recent example after adding borates. On Saturday I dropped pH from ~8.2 to 7.8 with about 50 oz of acid. I checked it yesterday and pH was at 8.0. So that's a daily increase of about 0.06, which is better, but obviously not great given it still takes about 3x more acid to produce the same pH drop after borates. I did not adjust yesterday since I was out of acid. My wife is getting more today. I suspect to go from 8.2 to 7.6 will take about 60 oz since I know 74 oz of acid takes me from 8.2 to 7.4 based on recent experience.

I try to keep TA at 70 because it just won't go any lower than that. The last time I checked I'd put it at 85 (post borate addition). Once you get it to 70 it seems to creep up to 80 slowly. I will try to lower it this weekend.

Thanks,

Ken

 

[JoyfulNoise]

Thanks for the info.

I'll say this - the borates are working.....

Before borates - 0.2 pH unit rise per day and 20oz of acid to down adjust pH

After borates - 0.06 pH unit rise and about 60oz of acid to down adjust pH

0.2/0.06 = 3.33

60oz/20oz = 3.0

When borates are applied to water, they do not change the total amount of acid needed over time. The only thing they do is slow the pH rise. So, if your pH rise slows by a factor of 3, then the amount of acid needed will also go up by a factor of 3. In other words, adding borates doesn't reduce acid usage, you will use the same amount of acid both before and after borates. The only thing borates do is stretch out the frequency a bit. In your case, the change wasn't all that big, so I can see why you're disappointed with it.

But here's the problem - plaster pools (with bad plaster jobs), along with fill water, will add alkalinity to the pool and thus put greater pressure on the pH. If your plaster is still emitting CaOH then that will cause pH to rise faster. Also, if the carbonate is dissolving from the plaster, that will make it harder to keep down the TA. If you can figure out your CH rise based on your evaporation rates (what you would expect theoretically) then any excess in CH rise, not from what you've added externally with the calcium chloride, will be related to the plaster as that is really the only other source of CH. There really shouldn't be anymore CaOH coming out of your plaster now that it is 15 months old, but a really bad plaster job where nodules may be forming or cracks that might expose the underlying plaster would cause such emissions. I doubt that's the case for your pool unless you're keeping your CSI too negative, in which case that can cause plaster to dissolve (although quite slowly).

 

[ta2dwonderwoman]

new to this whole swg thing and mostly commenting so I can follow along with this thread...but I am curious...I read that CYA is supposed to be between 70-80 when i set up my new system recently, but I see OP noted a CYA level of only 40 - could that have anything to do with any of this? likely not, but learning as I go

 

[JoyfulNoise]

new to this whole swg thing and mostly commenting so I can follow along with this thread...but I am curious...I read that CYA is supposed to be between 70-80 when i set up my new system recently, but I see OP noted a CYA level of only 40 - could that have anything to do with any of this? likely not, but learning as I go

CYA and borates add to the total alkalinity, but not as much as carbonates do. So the main effect of the low CYA is to just make the FC demand higher through sunlight loss. For the purposes of buffering, CYA doesn't do much at higher pH.