Ph rose from 7.47 to 7.95 in one day

[howardpassman]

Hello everyone. I'm new to posting, but have been using this site for a few years. Normally don't have much issue with my pool, but am curious about this one.
I check my pH, FC, CC, Alk daily. I use Clorox bleach with no additives (scents, etc.) to sanitize, using an average of 7-8 ounces a day to maintain around a 2-2.5ppm level. I do that because I use a mineral pack, which I realize most don't approve of. I've been using one of two types for 11 years now and not much out of the ordinary seems to happen.

Not sure why, but this year I have been having to add sodium bisulfate regularly. Approx 165 ounces (weight) in the month of August, not including today. The weather here hasn't been much good for swimming this year, meaning not sunny, but particularly wet at all. Because of that I've kept a solar cover on most of the time to keep evaporation down. About a week ago I noticed my pool getting a little dull. This week it has gotten much worse and I've been trying to correct it. Yesterday my FC was 3.6 and CC was .1. I added 40oz of 7.5% bleach to try to shock it. Today it looks worse and the pH has risen from 7.47 yesterday to 7.95 today. Here are the rest of my numbers today. FC 3.6, CC .1, pH 7.95, TA 90, Calc 255, CYA 50, TDS 725. My SI has been between -.06 to .03 until this week. This week it started at .06 and is now at .43. Not good. I have no aeration going on and the only abnormal thing this week is on Sept 1st we received about 1" of rain.

I can't think of anything else I can add. Since this is the first time I've posted, I'm hoping my signature pulls over with all the specs on my pool. If it doesn't, I will come back and edit this post. I appreciate any help I can get. Before I sign off, I have started adding Sodium Bisulfate to lower the pH today. I figure about 40ounces over the next two days.

Thanks,

Howard

 

[jblizzle]

Welcome to TFP!!!

You are on the verge or an algae bloom. You need to follow the ShockLevelAndMAINTAIN Process to clear up the pool.

And with a CYA of 50ppm, your FC is too low. The FC should never be below 4ppm if you want to protect yourself from disease transmission. See the FC/CYA Chart.

You may want to consider starting to use muriatic acid so that you do not keep building up sulfates in the water.

I have no explanation about he pH rise other than a general mistrust for the pH meters

 

[wjr75]

Your FC is too low for a CYA of 50. The CYA/Chlorine chart in pool school recommends never going below 4 with a target of 6. My CYA is around 45ppm and I tend to keep my target FC at 7ish ppm.

 

[svenpup]

I don't know anything about the pH meter you are using, but I do know that sometimes extra (false) precision give a false sense of accuracy. I find it hard to believe that the pH jumped .5 in a day without addition of anything basic or significant aeration.

There are several things that you are doing that are not recommended here:

We don't recommend long term use of dry acid since sulfates build up which can cause issues with staining as well as problems for SWCG's. For lowering pH we recommend muriatic acid.

As you mentioned we don't recommend mineral systems since this they can cause staining.

Your FC is low for your CYA level, which is probably what is causing the "dullness" you are seeing. You probably have an algae bloom about to take over.

You don't need to test TA daily. It shouldn't be changing that much.

TDS is irrelevant.

 

[howardpassman]

Thank you both for your replies and I will follow your recommendations. I was also suspect of the meter, which I just replaced this year. I occasionally check it against the Taylor kit and have twice this week as well and doing the 2 point calibration. It seems to be working well.

I'll never understand the CYA to FC thing as my CYA has been 50 to 55 all year and I keep my FC about 2-2.5. However, something is out of whack, so off I go to give it a try.

Thank you very much for responding so quickly!

Bests,

Howard

Welcome to TFP!!!

You are on the verge or an algae bloom. You need to follow the ShockLevelAndMAINTAIN Process to clear up the pool.

And with a CYA of 50ppm, your FC is too low. The FC should never be below 4ppm if you want to protect yourself from disease transmission. See the FC/CYA Chart.

You may want to consider starting to use muriatic acid so that you do not keep building up sulfates in the water.

I have no explanation about he pH rise other than a general mistrust for the pH meters

 

[howardpassman]

Thanks Svenpup. I am confident in the meter, because I do check it against the K2006 kit if it seems off and I do keep it calibrated.

I didn't know about the dry acid thing. Muratic seems confusing to me on how to add it, especially for small adjustments.

I don't worry about staining as my pool is black and over the years has bleached out in to a nice kind of psychedelic pattern

Please take this in the spirit I'm asking. I'm open to learning. However, I like to understand what I'm learning. My water has been crystal clear all year with the CYA at 50-60, most of the season around 50-55. I am semi-retired, so I test the pool mostly for fun and track a bunch of different things. I don't get why everything has been essentially the same all season and all of a sudden the water started looking dull and the pH took a leap.

Do you folks feel, *other than the staining*, the mineral packs don't work? Again, I've been using it for 11 years now and for the past two years I've been using daily doses of bleach for chlorination. Always keeping it around 2.5ppm. Am I just swinging in the wind trying to understand why it has all been working until now??

Thanks again for your patience. I really appreciate the help.

Howard

I don't know anything about the pH meter you are using, but I do know that sometimes extra (false) precision give a false sense of accuracy. I find it hard to believe that the pH jumped .5 in a day without addition of anything basic or significant aeration.

There are several things that you are doing that are not recommended here:

We don't recommend long term use of dry acid since sulfates build up which can cause issues with staining as well as problems for SWCG's. For lowering pH we recommend muriatic acid.

As you mentioned we don't recommend mineral systems since this they can cause staining.

Your FC is low for your CYA level, which is probably what is causing the "dullness" you are seeing. You probably have an algae bloom about to take over.

You don't need to test TA daily. It shouldn't be changing that much.

TDS is irrelevant.

 

[jblizzle]

Copper can help prevent algae. So the water will look fine, BUT, it does very little to kill bacteria, viruses, etc. So with the FC level lower than minimum for your CYA, the water is not really safe in terms of prevention of disease transmission.

If all you want is to keep the water clear, there are other products you can add without the risks of staining / green hair ... like polyquat 60 algaecides and lowering the phosphate levels. BUT again, without adequate chlorine, you could be at risk.

 

[howardpassman]

Sorry. Please disregard

- - - Updated - - -

Thanks again for the info. Not much left of the season here. I will try to get it cleaned up before we close it up.

Have a great night.

 

[wjr75]

I've read from Chem Geek that you need the chlorine to oxidize the bather waste which the mineral systems don't do. I had a Nature2 but took it out this year when I needed to fix a leak in my plumbing.

 

[RobbieH]

Above what has been said already, there is no reason to really care about FC at any increment less than .2, or even .4 for that matter. That is one of the reasons I hate pool store or automated reader results.

 

[chem geek]

Yes, chlorine is needed not only for disinfection but for oxidation. Unless, of course, one doesn't mind swimming in their own sweat and urine and dissolved chemicals from fecal matter.

 

[RobbieH]

MMM. Fecal matter.

 

[Swampwoman]

To the OP re ph spike...it sounded as if you read the ph AFTER you added a bunch of chlorine to start shocking. If your FC was higher than 10, that's ph reading would be false.

AND just for consideration...my buddy is a bonafide chemist who for 15 years added copper with his otherwise liquid chlorine diet. I'd warned him once I bought a house with a pool 3 yrs ago and learned about metal staining.

Last year and this, his wife and my BFF from afar will not swim because the pool is -- you guessed it -- turning her hair green

On his last visit I loaded him up with metal magic and he's now attempting to de-metal his pool...which can be tough once you hit the magic saturation number with copper.

So while your regimen has been largely successful for 11 years....do not trust that at some future point the copper won't catch up with you. It's your call, but as a blond, I super appreciate copper-free pools

 

[RobbieH]

I wouldn't consider that a spike. 7.47 to 7.95 is probably within the margin of error of his test method.

 

[howardpassman]

I always test before adding any chemicals. Always around the same time of day. My daughter has used the pool for half of her life and she is a blonde. Never noticed any tint to her hair. FC was 3.6 on the day in question. CC was .1 or .2. Robbie questioned my pH measurement, but I'm not sure how much better you can get than using a K2006 and a Hanna meter that gets calibrated. What else does a home owner have to do to get a good reading. Thanks for the info

To the OP re ph spike...it sounded as if you read the ph AFTER you added a bunch of chlorine to start shocking. If your FC was higher than 10, that's ph reading would be false.

AND just for consideration...my buddy is a bonafide chemist who for 15 years added copper with his otherwise liquid chlorine diet. I'd warned him once I bought a house with a pool 3 yrs ago and learned about metal staining.

Last year and this, his wife and my BFF from afar will not swim because the pool is -- you guessed it -- turning her hair green

On his last visit I loaded him up with metal magic and he's now attempting to de-metal his pool...which can be tough once you hit the magic saturation number with copper.

So while your regimen has been largely successful for 11 years....do not trust that at some future point the copper won't catch up with you. It's your call, but as a blond, I super appreciate copper-free pools

- - - Updated - - -

Hi Robbie. Don't know if you read my entire text, but I have always tested with a combination of the K2006 kit and a Hanna meter. My current meter is a few weeks old and I just calibrated it using the 2 point method. Normally my measurements are very consistent, hence my worry. If the margin on error is that high considering my tools and method, then why would anyone ever test their own water? I find I'm actually getting more confused since I posted the question than I have been foe the past 11 years.

I wouldn't consider that a spike. 7.47 to 7.95 is probably within the margin of error of his test method.

 

[RobbieH]

Yeah, ignore my post. I re-read, and realize now that I didn't read your figures correctly. Sorry about that.

 

[howardpassman]

WJR,
I'm pretty certain that all of the mineral systems have chlorine feeders. I know my original Frog system had one and the current Nature2 does. I quit using the feeders because you really can't control the amount of chlorine that goes in since it is always eroding the tablet and the demand is always varying. Since I really have nothing else to do with my time, I test daily and add bleach accordingly. Kinda fun graphing it out and seeing how well I do over the season.

I've read from Chem Geek that you need the chlorine to oxidize the bather waste which the mineral systems don't do. I had a Nature2 but took it out this year when I needed to fix a leak in my plumbing.

 

[Swampwoman]

Howard, metal preferences aside, and oxidization approaches aside, for the immediate problem at hand (nascent algae/dull water)
A) have you lowered your ph now so that you can more effectively shock your water
And
B) you said the following, which is why I thought you'd tested your ph AFTER shocking:

Yesterday my FC was 3.6 and CC was .1. I added 40oz of 7.5% bleach to try to shock it. Today it looks worse and the pH has risen from 7.47 yesterday to 7.95 today

-- but then said your FC was 3.6...which is not shock level for your CYA. Have you read up on the SLAM process? I only ask because I suspect 40 oz would not get you there...and of course, you need to hold it at that value to clean up the water...or as chem geek would say, oxidize it That's what you're doing when you shock it, and with lower chlorine levels all summer and perhaps more rain dragging organics into your water, it may well need a good SLAM to get sparkly.

 

[howardpassman]

Thanks swampwoman. Yesterday I added 242 oz of bleach which brought my FC to 10.8 this morning. I'll check it a little later and try to follow the SLAM guideline. On 9/4 I added 40oz of pH decrease to get it down from 7.95. On 9/5 it was 7.56. Today, 9/6/14, it is 7.97. And, please read how I check my pH. Again, today, my Taylor kit matches my Hanna meter as much as one can tell. The Taylor kit was flat out RED and the Hanna read 7.97.

So anyway, I am trying the SLAM method because I finally saw some algae in the pool yesterday. I didn't try the SLAM method earlier, just tried to shock it to get rid of the CC. Now that I see algae, well.....

I checked with my local pool store today and they are having a lot of complaints from folks who can't keep their pH down this year. I have no idea why and they didn't either. We've had very little rain with the exception of the 1" we got on 9/2 and maybe a 1/4" 9/3.

I'm trying not to be contrary on the silver/copper thing, but I really don't understand TFP's hardline against something that even NASA uses to purify water. Is it the form that's used? The concentrations? I'm definitely not a chemist, but so far what I've read outside of this forum seems to state that silver/copper ionization reduces the need for as high of level of chlorine by a fair percentage. The APSP lists 2-4 ppm of FC as ideal. I felt that somewhere in that range, the combination of chlorine and the mineral pack, I'd be good. I agree my CYA is a bit high.

What I originally came to the forum for was an explanation of what might be causing my pH to jump so quickly and instead what I got was several unrelated lectures. Apparently, I do have algae and I do appreciate the guidance on the SLAM method. I would still love for someone to tell me what may cause a jump in the pH and not scold me for using inaccurate test methods(I disagree), mineral packs and drinking too much

Have a great weekend.

 

[chem geek]

I'm trying not to be contrary on the silver/copper thing, but I really don't understand TFP's hardline against something that even NASA uses to purify water. Is it the form that's used? The concentrations? I'm definitely not a chemist, but so far what I've read outside of this forum seems to state that silver/copper ionization reduces the need for as high of level of chlorine by a fair percentage. The APSP lists 2-4 ppm of FC as ideal. I felt that somewhere in that range, the combination of chlorine and the mineral pack, I'd be good. I agree my CYA is a bit high.

It's the risk of metal staining especially against plaster surfaces and also the risk of turning blond hair greenish. If those risks weren't present, then we'd likely put copper ions in the same bucket as Polyquat 60 for algae control. It's not necessary because maintaining a proper Free Chlorine (FC) to Cyanuric Acid (CYA) ratio prevents algae growth.

With CYA in the water, the active chlorine level is low at around 0.06 ppm FC equivalent with no CYA for our minimums for non-SWG pools. That 7.5% FC/CYA ratio is what is needed to prevent green and black algae growth regardless of algae nutrient (phosphate, nitrate) level. If one wants to go below that FC/CYA level, then one would need to use an algaecide to prevent algae growth, though the disinfection rate would also be lowered as well. Though clearly in your case your copper ions aren't working to prevent algae at this point in time, possibly because their level has dropped or because you have more algae nutrients now and the copper level isn't sufficient (while earlier that level was enough when algae nutrient levels were lower).

I think you've got stuck in your brain that a high FC number means something bad in terms of having a lot of chlorine. It doesn't. The FC is the chlorine reserve since most of it is bound to CYA and inactive. The amount of chlorine that is unbound to CYA and is what disinfects, kills algae, and oxidizes swimsuits, skin, and hair is that very low 0.06 ppm amount. So if the only reason you are trying to go lower is this incorrect thought of the FC number meaning something that it really doesn't, then try to get your head around that. The only issue for a high FC would be if you were to drink lots and lots of pool water, but to get to the EPA limit of 4 ppm FC with 2 quarts a day for a lifetime, at 8 ppm FC you'd still have to drink a quart of pool water every day for the rest of your life and you'd still be at the 1 in a million increased cancer risk the EPA uses for their limits. And of course, you aren't drinking pool water in any such quantities so this is really irrelevant.

As for disinfection, as described in detail in this post, copper alone does not kill fecal bacteria and copper and silver together kill bacteria slowly, do not effectively inactivate viruses, and do not kill protozoa or inactivate their oocysts. The reason the metal ions work for NASA is 1) there is not a constant introduction of fecal matter with new bacteria, viruses, protozoan oocysts, etc. in the drinking water supply and 2) there is plenty of time for a slow kill of any residual pathogens in the drinking water. In a swimming pool without proper disinfection there is not only the risk of uncontrolled bacterial growth but also the risk of person-to-person transmission of disease. That is why the EPA requires a fast-acting disinfectant in the bulk pool water. The use of off-line systems such as UV or ozone do nothing to prevent pathogen transmission or even growth if stuck on pool walls and not circulated. The use of slow-acting metal ions do not kill quickly enough to meet EPA's Swimming Pool Disinfectants standard DIS/TSS-12. The only EPA-approved disinfectant chemical types for swimming pools are chlorine, bromine, and Baquacil/biguanide/PHMB.

Ignore the APSP, NSPI, CDC, EPA, state code, and everything else you've read (except for peer-reviewed scientific papers in respected journals) because none of them understand the FC/CYA relationship even though it's been known definitively since at least 1974. You can read more about this relationship in the "Chlorine/CYA Relationship" section of the thread Certified Pool Operator (CPO) training -- What is not taught. Specifying an FC range without referencing the CYA is ridiculous since the FC/CYA ratio (when CYA is present) is what determines the level of active chlorine that disinfects and oxidizes.

As for why your pH rose so quickly, we simply do not know since you haven't told us anything that would give us a clue as to the reason (you gave us info, but none of it is consistent with a rise in pH). If you see any breaks in your plaster with volcano-like formation of calcium carbonate on the floor or streaks of it on the walls then I'd say you had Calcium Nodules in your pool and the calcium hydroxide that gets exposed to the water and converted to calcium carbonate can raise the pH. If you had a change in aeration (rainfall, waterfalls, spillovers, fountains, pool usage including splashing) or longer pump run time then that can have more carbon dioxide outgassing causing the pH to rise more. If you used a different source of chlorinating liquid or bleach, then it might have more excess lye in it though that usually isn't enough to be noticeable in such a short time. If you used to use a net acidic chemical such as Dichlor, Trichlor, or non-chlorine shock (MPS) and this year stopped using it then perhaps your pH was kept in check with those chemicals and now it isn't. If you add a hypochlorite source of chlorine the pH will rise temporarily as the FC rises, but you compared pH on two days with the same FC level. If you accidentally added pH Up or similar product instead of the intended acid, then that would raise the pH quickly. Again, these are just guesses because nothing you mentioned would point to a reason for more rapidly rising pH that we normal know about.

You did notice, at least most recently, that the pool water was getting cloudy, possibly from algae, so maybe the algae growth is causing a rise in pH though normally we don't see that. However, this paper implies that algae growth will tend to move the pH towards the 8.5-11.0 range so maybe that is what happened. If the cloudiness was from plaster deterioration (calcium nodules) then as I noted above that would raise the pH as well. However, you said that this entire season you've had to add more acid, not just recently. Perhaps you had nascent algae growth that wasn't yet visible and that tended to have the pH rise.