pH Adjustment Frequency before and after borates

[kwhoward]

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).

Thank you Matt,

Given your enlightening math explanation, maybe going up from 40 to 50-55 ppm borates could further slow the rise? What do you think? If overall acid usage is truly the same, then what do I have to lose?

There's definitely no cracks in my plaster and it is nice and smooth with no nodules forming. CSI right now is -0.14 to -0.22 per the calculator depending on pH.

I'm bad about putting my pool cover on, so here in dry CA my evaporation might be fairly high.

 

[JoyfulNoise]

Thank you Matt,

Given your enlightening math explanation, maybe going up from 40 to 50-55 ppm borates could further slow the rise? What do you think? If overall acid usage is truly the same, then what do I have to lose?

There's definitely no cracks in my plaster and it is nice and smooth with no nodules forming. CSI right now is -0.14 to -0.22 per the calculator depending on pH.

I'm bad about putting my pool cover on, so here in dry CA my evaporation might be fairly high.

I looked up Chino Hills and see that you're in the Inland Empire so, yes, evaporation is high. I'm horrible at covering my pool and Tucson has over 90" of evaporation per year so I basically exchange my entire pool volume in one year. As such, my CH rises 250-300ppm/year and, with 4 year old water, I'm already at 1100ppm CH and so I will be draining soon. It's still possible to keep a pool balanced with CH over 1000ppm, but it's not fun.

You could try raising your borates up to the 50ppm mark. I know in my own pool that borates don't seem to do anything until I get to about 40ppm and 50ppm seems to work a lot better than 40ppm. I'm at 46ppm right now and my plan is to add enough boric acid to get close to 60ppm. I'll see how that helps with my pH rise since being at 1100ppm CH I need to keep my pH in the 7.5-7.7 range and the pH rise is a lot faster once you start going below 7.6. If I can make my pool hover at a pH of 7.7 and a TA of 60, then my water will be fine in terms of CSI (-0.2 to 0 range).

Also note that with high evaporation rates, you add a lot of fill water. Your fill water is at 70-80ppm which is good (mine is anywhere from 100-120ppm) but there is still going to be upward pressure on your pH from that alkaline fill water. When I tried covering my pool last spring, it was interesting to see the pH rise all but stop and I used no acid for the entire month that the pool was covered. Once I replaced my pool water, I will be looking into various options to keep the CH down - using rain water captured from my roof for fill, putting a softener on the fill line and finding a better way to keep my pool covered.

 

[kwhoward]

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).

Thank you Matt.

One last thing I forgot to mention... I noticed for several months now that I see a lot of bubbles through the clear pump lid. The overall air bubble on high is pretty small, maybe 2.5 to 3 inches in diameter in the dome. The bubbles appear regardless of suction source (pool vs. spa). I've cleaned the lid seal thoroughly and lubed it with silicon spray. I ran water around the base of the lid and all suction pipes/joints/valves a while back in and effort to look for a suction side leak and saw no reduction in the bubbles. Could all of these bubbles have a constant aeration effect, thus contributing to pH rise? I highly doubt there is a leak in the pipes since the sources are independent of each other pipe wise. Also, I saw them do the pressure test and the needle didn't budge for at least 24 hours. With the SWG off, no bubbles come out of the pool's return jets.

 

[JoyfulNoise]

Thank you Matt.

One last thing I forgot to mention... I noticed for several months now that I see a lot of bubbles through the clear pump lid. The overall air bubble on high is pretty small, maybe 2.5 to 3 inches in diameter in the dome. The bubbles appear regardless of suction source (pool vs. spa). I've cleaned the lid seal thoroughly and lubed it with silicon spray. I ran water around the base of the lid and all suction pipes/joints/valves a while back in and effort to look for a suction side leak and saw no reduction in the bubbles. Could all of these bubbles have a constant aeration effect, thus contributing to pH rise? I highly doubt there is a leak in the pipes since the sources are independent of each other pipe wise. Also, I saw them do the pressure test and the needle didn't budge for at least 24 hours. With the SWG off, no bubbles come out of the pool's return jets.

Double check the drain plug on the wet end. There are two plugs - one that drains the front of the wet end where the strainer pot is and the other drains the volute after the impeller and so that would be the discharge side of the wet end. Make sure the o-ring on the strainer pot plug is in good shape and properly lubed.

I've always had an air bubble show up in my strainer pot. I can make it go away by running the pump on high speed for a little while but it eventually returns. It's never bigger than what you say (2"-3" in diameter) and my pump never loses prime so there's no air leak. I have seen what looks like the occasional small bubble emanate for the where the lid gasket is and so I surmised that it is probably a very tiny leak in the strainer lid gasket (I need to replace mine) but it only shows up at high speed which would be when the strainer pot is under vacuum from the pump. It's very minor and it doesn't bother me in the least or affect the performance of my plumbing system as far as I can tell. There's no air bubbles coming out of the returns except when the SWG is running and it is producing hydrogen gas.

You would not and should not see any bubbles when the SWG is off as those tiny bubbles are typically the hydrogen gas that the SWG produces. It does cause aeration and that will cause pH rise in an SWG pool. The bubble in your strainer pot has no effect on your water chemistry.

 

[kwhoward]

Double check the drain plug on the wet end. There are two plugs - one that drains the front of the wet end where the strainer pot is and the other drains the volute after the impeller and so that would be the discharge side of the wet end. Make sure the o-ring on the strainer pot plug is in good shape and properly lubed.

I've always had an air bubble show up in my strainer pot. I can make it go away by running the pump on high speed for a little while but it eventually returns. It's never bigger than what you say (2"-3" in diameter) and my pump never loses prime so there's no air leak. I have seen what looks like the occasional small bubble emanate for the where the lid gasket is and so I surmised that it is probably a very tiny leak in the strainer lid gasket (I need to replace mine) but it only shows up at high speed which would be when the strainer pot is under vacuum from the pump. It's very minor and it doesn't bother me in the least or affect the performance of my plumbing system as far as I can tell. There's no air bubbles coming out of the returns except when the SWG is running and it is producing hydrogen gas.

You would not and should not see any bubbles when the SWG is off as those tiny bubbles are typically the hydrogen gas that the SWG produces. It does cause aeration and that will cause pH rise in an SWG pool. The bubble in your strainer pot has no effect on your water chemistry.

I'm pretty confident the plugs are tight because I had both out when I used pressure and vacuum gauges to get readings for calculating total head. It was fun to do, but I had estimated 70 feet of head and sure enough, it was 70 on high. I was more interested in the head on low so I could calculate run time on low. I inspected both plugs and the O-rings. All looked good and I got them back in tightly. However, you can bet I will run my hose right over the strainer side plug just to check before fussing with it. BTW... The bubbles were there before I removed the plugs. My pump has never lost prime either.

Also, to be clear, the small bubbles I see are independent of the overall "dome bubble". I watched closely and they almost appear to emanate from within the basket, though I can clearly see some bubbles coming into the pumps intake if I watch closely. Maybe there's a leak in the strainer side plug. Who knows?

Thank you.

 

[zollan23]

Ken,

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



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.

This really concerns me... "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)."

To me, this should be more widely discussed, especially in pool school or other Borate how-to's. I also thought one of the main reasons to use it was SWG and/or new plaster pools because of the constant increase in pH... Hence the need.

To risk it not working and then have to use even more acid to lower pH seems like a risk not worth taking, yet this is the first I'm hearing of it. Can we add this to the how-to threads.

I just added 50ppm of Borates. It's only been about 5 days, but early indications are that my pH is rising the same as it was before - 0.1 every day, like clock work. If it now takes my 2x the acid to lower, I'm in the same spot and truly frustrated.

 

[Bperry]

This really concerns me... "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)."

To me, this should be more widely discussed, especially in pool school or other Borate how-to's. I also thought one of the main reasons to use it was SWG and/or new plaster pools because of the constant increase in pH... Hence the need.

To risk it not working and then have to use even more acid to lower pH seems like a risk not worth taking, yet this is the first I'm hearing of it. Can we add this to the how-to threads.

I just added 50ppm of Borates. It's only been about 5 days, but early indications are that my pH is rising the same as it was before - 0.1 every day, like clock work. If it now takes my 2x the acid to lower, I'm in the same spot and truly frustrated.

Read through a bit more. It doesn’t take more or less acid to affect the same pH reduction, it just slows it down. So you’ll add the same amount over time, just less frequently. It may just be that the effect isn’t very noticeable for you.

I’ll say that those borate test strips are pretty bad. The first one seemed to work ok, but they went bad a month or so after unsealing the bottle. So be careful with assuming what the borate level is. I’ve found that as my TA has lowered the pH is way more stable. I have to acid maybe every other week now.

 

[zollan23]

Read through a bit more. It doesn’t take more or less acid to affect the same pH reduction, it just slows it down. So you’ll add the same amount over time, just less frequently. It may just be that the effect isn’t very noticeable for you.

I’ll say that those borate test strips are pretty bad. The first one seemed to work ok, but they went bad a month or so after unsealing the bottle. So be careful with assuming what the borate level is. I’ve found that as my TA has lowered the pH is way more stable. I have to acid maybe every other week now.

Is there a better recommendation on getting an accurate Borate reading? Pool store?

I understand I have to use the same acid amount justess frequently, but I'm my quote it was saying sometimes it just doesn't work. So you're adding more acid with the same frequency. That's a nightmare.

I will work to get my TA lower. That is so harder now that I have Borates in the pool but it seems like that's been helpful for others.

 

[AUSpool]

Is there a better recommendation on getting an accurate Borate reading? Pool store?

I understand I have to use the same acid amount justess frequently, but I'm my quote it was saying sometimes it just doesn't work. So you're adding more acid with the same frequency. That's a nightmare.

I will work to get my TA lower. That is so harder now that I have Borates in the pool but it seems like that's been helpful for others.

There is, its the mannitol borate test. New borate drop test at piscines-apollo vs. test strip A little involved but more accurate. For now I’m using my strips, I know my starting point from my borate addition from zero and can monitor any change by following my salt levels. It’s a bit crude but it works for now. I’ll renew my reagents and do the mannitol test again next year.

I have found the borates to work as described. If you find yourself adding more acid with the same frequency with borates then I would assume something is no right.

 

[bloodocean]

I dumped borates in my brand new pool this winter and continued to have high acid demand until 6 months or so had passed.

I went from 4 cups every 2 days to about 2 cups per week.

 

[zollan23]

I dumped borates in my brand new pool this winter and continued to have high acid demand until 6 months or so had passed.

I went from 4 cups every 2 days to about 2 cups per week.

I feel like some days it works and some days it doesn't. Red flags for me are a similar daily rise in pH and when adding acid, the pH drops pretty quickly. I know I have at least 40ppm of Borates and by reading the strips I see 60ppm. For me, I feel like it is having no impact on acid demand. Frustrating

 

[Bperry]

I feel like some days it works and some days it doesn't. Red flags for me are a similar daily rise in pH and when adding acid, the pH drops pretty quickly. I know I have at least 40ppm of Borates and by reading the strips I see 60ppm. For me, I feel like it is having no impact on acid demand. Frustrating

If the bottle of strips has been open for more than a week, they have probably gone bad. I had a similar issue where they were reading at 75ppm after the bottle had been opened (but cap on) where I only added about 30ppm and had the strips testing at about the same amount previously.

 

[TexasEd]

I plan to eventually add Borates but will wait until my plaster is at least a year old based on the discussion here and elsewhere. It just seems, anecdotally at least, that having mature plaster is the prudent approach.

 

[zollan23]

I feel like my borates are accurate. I can feel the difference in the water and see the clarity. Strips lasting only a week seems like a one-off. They have a shelf life longer than that, surely. According to Taylor, the Borates strips have a shelf life of two years.

 

[Bperry]

I feel like my borates are accurate. I can feel the difference in the water and see the clarity. Strips lasting only a week seems like a one-off. They have a shelf life longer than that, surely. According to Taylor, the Borates strips have a shelf life of two years.

Shelf life means “with the bottle sealed”, once the bottle is opened, all bets are off. Evidently I’m not the only one to have experienced it. A week is probably shorter than reality but mine were way off after a month from first use. I would not trust any borate levels they indicate after about a week.

 

[zollan23]

Shelf life means “with the bottle sealed”, once the bottle is opened, all bets are off. Evidently I’m not the only one to have experienced it. A week is probably shorter than reality but mine were way off after a month from first use. I would not trust any borate levels they indicate after about a week.

Good to know... Terrible.

 

[Bperry]

Good to know... Terrible.

Perhaps in southern CA you might have better luck after they’re opened than in places with higher humidity like we have.