PH is always high

[jcm0020]

I've been following this website for 4 weeks now. I drained my pool halfway to bring my CYA and CH down (CYA was 100+ and CH was 500). Now my battle is keeping the PH in the recommended level of 7.5-7.8 for plaster pools using bleach. I'm constantly adding Muriatic Acid every day I add bleach (not at the same time). I have read that bleach has a PH of 13 which would explain why my PH rises when I add chlorine. Big bottles of bleach and big bottles of muriatic acid are a pain to haul around the pool daily.

FC: 9 (added extra bleach because of rain in the forecast)
PH: 7.8 (was 7.5 before I added bleach)
TA: 80
CH: 260
CYA: 65-70

I also have 2 small waterfalls plus a spa overflow into the pool.

Is there anything I can do to help stabalize my PH or is this just something I have to deal with because of using bleach?

Thanks in advance for your help.

Jason

 

[JohnT]

The pH increase from bleach is only temporary, but high chlorine levels can make the pH test read high.

 

[TravisD]

From what I understand, bleach is for the most part PH neutral.
The aeration from your waterfalls could be what it causing it to rise. Aerating will make your PH rise.

 

[dravenone]

Ditto what Travis D said. Any way you can turn off a couple of those water features??

 

[jcm0020]

Yes there is. What a great idea. I'll turn them off for a few days and see how it does.

 

[Gooserider]

As I understand it, adding borates can also help stabilize the pH... Does lots of other good things as well, so I highly reccomend them for most folks. It also seems to me like your TA is a bit on the low side - TA is a big part of your pH buffer, and getting the TA up may help lock your pH in a bit better...

If you look at the pool school, it sounds to me like all those water features and your current practices are effectively having you follow the exact instructions for lowering TA - drop the pH and aerate... I'd bump the TA back up to around 100, and see where your pH ends up at on it's own.

In our quite old gunnite pool I initially had high TA (125) back in the spring. Over a few days I dumped in a couple gallons of MA, and aerated w/ a home made aerator (we don't have any regular water features), added borates and since then have been essentially locked at pH 7.5-7.8 and TA 100-110,

Gooserider

 

[Guest]

DO NOT RAISE THE TA! That is incorrect information. If anything lower it a bit more to lower the outgassing of CO2 from the aeration, which is what is causing your pH rise (Unless your pebbletec is less than a year old, then the acid demand is from the alkaline material leaching from the plaster. It can take up to two years sometimes for that to stop). Borates can also help.
You might find these threads useful:
ta-what-is-it-really-t4979.html
how-to-lower-ta-t5341.html
so-you-want-to-add-borates-to-your-pool-why-and-how-t4921.html

The first one will explain why your pH is rising.
The other two are HOWTOs with some info you might find useful.

 

[Guest]

TA is a big part of your pH buffer, and getting the TA up may help lock your pH in a bit better...

Raising the TA does not "lock in pH". What it does is cause the pH to move toward 8.3 faster than if the TA is low. This is because the higher the TA (bicarbonates in the water), the faster CO2 will outgass (since the carbonation of the pool is higher). The faster the outgassing the faster the pH rise. Now this pH rise can be a good thing when using acidic sanitizers like trichlor, dichlor, chlorine gas, bromine, or using MPS to shock since they all cause the pH to drop but is the opposite of what we want when using any of the hypochlorite forms of chlorine, including bleach and SWGs, since these unstabilized chlorine sources are essentially pH neutral (they are akaline when added but the reaction of hypochlorite giving up it's oxygen, which it does when it breaks down from either sanitizing or from sun, and becoming chloride ion is acidic so the net effect is pH neutrality).
You might find that this thread is helpful in explaining exactly what TA is and does:
ta-what-is-it-really-t4979.html

Bottom line, if you pH is always falling too fast then raise the TA, if it's rising too fast then lower the TA.
If it's bouncing all over the place than raise it up until it becomes stable. This is usually seen with acidic santizers like the stabilized chlorines and bromine.

TA buffers mostly in the upward direction. The advantage of adding borates is that, unlike the carbonic acid/bicarbonate buffer we call TA the boric acid/borate buffer tends to buffer more in the downward direction. Together they have a synergistic effect of stabilizing the pH for longer periods of time than just the bicarbonate buffer alone.

 

[Gooserider]

Sorry if I mis-spoke - however this seems to be the effective result in my pool...

Cl - varies alot because I don't test and add more as often as I should I have had it get down to .5 a few times, and usually target bumping it up to 5 or so. I have probably been pushing the algaestatic properties of the borates kind of hard, but my water has never looked so good back when I was being pool-stored. I had ONE day where I noticed the water was looking a touch murky, (or what I used to think of as normal...) and had ZERO FC, and .5 CC - bumped it to shock level, and the next day it was back to perfect.

I did the lower pH w/ Muriatic Acid and aerate stuff around the end of May, and added about 65 parts of borates, since then my pH has been between nearly constant at 7.5-7.8. My TA has been almost as stable - it was at 110 on 6/3/09, two days after my last addition of MA and about four after my last borate addition. Since then it has very slowly drifted up, and today it hit 120, with pH still at 7.8...

My CH has been holding steady at 260

I have just gotten back in from adding about 3/4 gallon of MA and hooking the aerator back up in an effort to get the TA back down to about 100-110. This was the first time I added anything besides bleach since 6/1/09

Gooserider

 

[Guest]

I have just gotten back in from adding about 3/4 gallon of MA and hooking the aerator back up in an effort to get the TA back down to about 100-110. This was the first time I added anything besides bleach since 6/1/09

Gooserider

Shoot for about 80 instead. Your pH will be even steadier. If your TA drifted up on it's own then it's probably from your fill water. What is the TA of your fill water? If it is higher than where you keep the pool TA then when you do lower the TA in the pool shoot for the low end of the range, around 70-80 ppm and bump up your CH a bit to around 300 ppm.

 

[Guest]

Sorry if I mis-spoke - however this seems to be the effective result in my pool...

However, you did not raise your TA from a low number to 100, you lowered it down from a higher number down to 100. If you would have lowered it even more you would have better pH stability.

Cl - varies alot because I don't test and add more as often as I should I have had it get down to .5 a few times, and usually target bumping it up to 5 or so. I have probably been pushing the algaestatic properties of the borates kind of hard, but my water has never looked so good back when I was being pool-stored.

NOT a good idea. Borates might be an algaestat but they are NOT a sanitizer. Remember , clear water is not always sanitized water and the primary job of chlorine in your pool is NOT to keeep algae away but to keep the water sanitized and prevent the spread of water borne illnesses.

 

[Gooserider]

I have just gotten back in from adding about 3/4 gallon of MA and hooking the aerator back up in an effort to get the TA back down to about 100-110. This was the first time I added anything besides bleach since 6/1/09

Gooserider

Shoot for about 80 instead. Your pH will be even steadier. If your TA drifted up on it's own then it's probably from your fill water. What is the TA of your fill water? If it is higher than where you keep the pool TA then when you do lower the TA in the pool shoot for the low end of the range, around 70-80 ppm and bump up your CH a bit to around 300 ppm.

Not sure what the fill water TA is, especially not this year when the only tap water I've added has been minor stuff like when I first primed the pool pump, incidental overspray when rinsing something off... When I closed last fall, I pumped down to about 6" below the returns, between the snow and rain draining through the safety cover the pool was full when I opened, and we have had so much rain since the pool has been continuously full to over-full...

I've never added anything specifically to change the CH - that seems to be where it stays.

I tried doing the lowering TA thing of dumping in acid and aerating, and got it from my initial test of 125 down to about 100 before adding the borates, which bounced me back up to around 150-160 for a day or two and then came back down w/ the help of plenty of acid and aeration, but it has been pretty stable since. I'm hoping this round will get the TA lower, but I'm not going to worry about it that much - if the present pattern continues, my pH should be fine until we close towards the end of September.

As to the water sanitizing thing, I agree, I should do better, but I don't see a huge need to panic about it... The GF and I are basically the only ones that use the pool (aside from possibly a few critters - I fish lots of dead mice, toads, frogs, bugs, etc out of the skimmer) and we have much easier (and more fun) ways to give each other anything we might have... If I did plan on guests, I would certainly be bumping the pool up to near shock levels before and after. Given the light and limited bather load, I'd be surprised to see our pool be a vector from the side that there isn't a source to start the infection...

Gooserider

 

[Guest]

Is your pool outside? Do birds fly over it? Do cirtters get into it? Keep it sanitized. Water borne illnesses are NOT a joke.

No matter how clean you think you are, every time you enter the pool you add sweat, urine, and feces to the water. So does your GF.

 

[jcm0020]

What is the lowest I should have my TA when using bleach as the primary sanitizer? I've had it down to 70 and shut off my water falls but the PH always goes up to 8 when I add the bleach sanitizer. It only takes about a day for the PH to rise from 7.5 to 8 after adding bleach. I am thinking about raising my TA to 100-110 just to see what would happen to my PH even though it is not advised to do so. I don't like adding bleach then adding MA (about 4-8 hours apart) or vice versa every time I sanitize.

 

[frustratedpoolmom]

Bleach will cause a temporary rise in PH but as the chlorine is used up the PH goes back to the level prior to adding it. You shouldn't test PH after adding chlorine and then adjust with MA - those readings are not necessarily accurate.

Test PH before adding any chlorine. Keep it in the 7.4-7.6 range. You want your TA in the 70-90 range - raising it up will cause the PH to rise more, especially when using a water feature.

 

[jcm0020]

let's say for example that my PH is at 7.5 before I add bleach then after adding my bleach the PH rises to 7.8-8. do i assume it's OK and leave it as is?

 

[chem geek]

If you use Clorox Regular unscented bleach, then adding 5 ppm Free Chlorine (FC) would raise the pH from 7.5 to 7.7-7.8 if the TA was 70 ppm. The consumption/usage of the chlorine would bring the pH back to to 7.5 by the next time you add chlorine. If the bleach you are using has a lot of excess lye in it, then the pH could rise more initially and not fall back as far, but even assuming 2 ppm FC per day with Ultra bleach that has a pH of 12.5 you are looking at a pH rise of 0.2 units per month.

If you are only adding 2 ppm FC and see a large pH rise, then something is wrong. Try changing the brand of bleach to Clorox Regular unscented and not an off-brand Ultra bleach to see if that makes any difference. Also, as frustratedpoolmom mentioned, measure your pH at the same FC level each day, so before you add the bleach. As for a pH target, you don't have to get down to 7.5 and could instead target the 7.6 to 7.8 range as that could be more stable. Finally, as was mentioned by others, you can get more pH stability if you use 50 ppm Borates in the pool.

There are other possible sources of pH rise including curing of plaster if you had your pool recently replastered or if it is new, but usually such significant rise in pH slows down quickly over months and after a year it's far less and often not noticeable.

As for how low a TA can go, I wouldn't go much lower than 70 ppm given your CYA level of 60-70 ppm though there are some users who have gone as low as 50 ppm and raised their CH and pH targets accordingly.