Is our SWG too powerful for our small pool?

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Rachelmarie

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Sep 14, 2018
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Tampa
The SWG they installed is made for pools up to 40k gallons and our pool is only 5k. Pool is over 2 months old and we can never get the ph under control no matter how much acid we add. ph was 8 and TA around 100 and we added 24 oz yesterday and ph stayed at 8. I am wondering if the SWG being too powerful could be part of the problem?
 
What is the FC running?
No matter how "powerful" the SWCG is, if it's only maintaining the reqired FC it's not affecting the pH rise any more than a smaller one.

It would also help if you posted a full set of test results and how you got them?
pH
FC
CC
TA
CH
CYA
 
Your SWG affects your FC and has little effect on your pH. You should have your SWG set at a low runtime .

What is the % output of the SWG and how long does it run for daily?

Most of the time your SWG should be effectively off.
 
If your pool was just finished in 12/18 you are going to be battling pH rise while the plaster continues to cure. Also how are you testing the pH? The pH test kit doesn't have an 8.0 reading. It goes up to 8.2, so odds are good your pH is much higher. How long do you wait after adding acid to retest the pH?
 
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Typically we install SWG that are twice the normal size for the pool size due to longevity and minimal output so you are in good shape there. As far as ph not being affected by the SWG is not correct. It’s producing chlorine through the day even in small amounts and chlorine does have an effect on PH which it will drive it high through out the week. I believe your ph level has more to do with curing then the SWG though. 8.0 or higher is definitely from the new surface break in. It will come down over time. Quite normal. Enjoy
 
Srqpoolguy said:
As far as ph not being affected by the SWG is not correct. It’s producing chlorine through the day even in small amounts and chlorine does have an effect on PH which it will drive it high through out the week.
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@duraleigh says it ain't so. You two can duke it out in the Deep End. I have said as much and been corrected.
 

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RachelMarie- from your other threads recently-->

Did you ever drain and refill the pool to get the bromine out of it that you added??

Did you ever obtain the TF-100 test kit (or the K2006C) you have been repeatedly suggested to buy or are you still going to the pool store for testing?

Maddie :flower:
 
Yea and smart move. Always get a bigger cell then required. But I know for a fact your surface is causing the level of ph in your pool. One day you will notice it will come down all a sudden. I do break ins all the time. They make add in chemicals you can add such as certain sequestering liquids that can help with the break in and ph control in the beginning but it is not required. Enjoy!
 
Srqpoolguy said:
...chlorine does have an effect on PH which it will drive it high through out the week...
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Liquid chlorine or bleach has a high pH but the sanitising and degradation from UV reactions are acidic. The net result produces close to zero effect on the pool pH.
 
Close to but not quite. Almost every salt pool we service (467) needs a ph adjustment every week of a small amount. We had a guy named Jim from stain drop (ex jacks) speak to my company about this and they said the number one problem of salt water pool finishes is scaling and a direct result is high ph for prolonged periods. Coincidence? Not at all. I think the real issue is the home owners or even pool guys run the SWG at a much higher output than necessary and that is a direct result. So to say that there is no ph change with a salt water pool is simply not accurate. Of course other factors here too as we know such as alkaline levels etc. I’ve heard the uv theory yes but there is to much proof otherwise.
 
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Srqpoolguy said:
Close to but not quite. Almost every salt pool we service (467) needs a ph adjustment every week of a small amount. We had a guy named Jim from stain drop (ex jacks) speak to my company about this and they said the number one problem of salt water pool finishes is scaling and a direct result is high ph for prolonged periods. Coincidence? Not at all. I think the real issue is the home owners or even pool guys run the SWG at a much higher output than necessary and that is a direct result. So to say that there is no ph change with a salt water pool is simply not accurate. Of course other factors here too as we know such as alkaline levels etc. I’ve heard the uv theory yes but there is to much proof otherwise.
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Welcome to the forum!

I would like to direct you to this thread: What causes pH rise in pools with SWGs?

A polite reminder that we don't accept "That's my experience so it's true" when chemistry does not back up a statement. If you are seeing a constant pH rise in your SWG pools then you are likely keeping your TA too high. Allow that to drop and you will find the problem quickly clears up.
 
Rachelmarie said:
The SWG they installed is made for pools up to 40k gallons and our pool is only 5k. Pool is over 2 months old and we can never get the ph under control no matter how much acid we add. ph was 8 and TA around 100 and we added 24 oz yesterday and ph stayed at 8. I am wondering if the SWG being too powerful could be part of the problem?
Click to expand...

Rachel,
If you're able to adjust the SWG to maintain the proper FC level then it's working fine. It is not possible that the size of your SWG is the problem if you are keeping FC in range. I would keep checking the pH and make additions to slowly drop to an acceptable range. Here are a couple of things for you to consider as you battle the pH problem:
  • I have several friends in the pool business that indicate pH does seem to rise with SWG pools but they all say it is very manageable with slight acid additions. I would guess the bigger problem with your pH is the pool is pretty new. I had similar problems during start up and many new pools have the same issue whether they are salt or not.
  • After a new pool gets stabilized the pH is easier to control. Also make sure to monitor TA as it can make pH control difficult. There's a good write up on this in pool school and on other posts in this forum.
  • pH measurements are not accurate if your FC is over 10.
  • Acid addition calculations are only accurate for narrow range changes of pH.
  • As one post mentioned you could have gotten a pH much higher than the pH test detects and so your pH was much higher than you realized. A drawback of the test is that it does not change color above 8.2. So you could have been 8.8 and not realized it. Your acid additions could have dropped it .2 or so and you wouldn't know until you get down to the pH levels that the test can discern.
  • Aeration raises pH. If your pool dimensions have a large surface area to depth ratio this exacerbates the aeration affect. Turn off a spill-over or any water features until you have the pH under control.
I hope this is helpful.

Chris
 
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Srqpoolguy said:
Close to but not quite. Almost every salt pool we service (467) needs a ph adjustment every week of a small amount. We had a guy named Jim from stain drop (ex jacks) speak to my company about this and they said the number one problem of salt water pool finishes is scaling and a direct result is high ph for prolonged periods. Coincidence? Not at all. I think the real issue is the home owners or even pool guys run the SWG at a much higher output than necessary and that is a direct result. So to say that there is no ph change with a salt water pool is simply not accurate. Of course other factors here too as we know such as alkaline levels etc. I’ve heard the uv theory yes but there is to much proof otherwise.
Click to expand...

I'd happily argue with anyone about this topic and I'd win because the chemistry is settled. Please see this post in our Pool Water Chemistry thread written long ago by an expert in chemistry -

Pool Water Chemistry

(Unfortunately, due to our forum software update, the BBcodes for superscript and subscript are not working so it makes reading the chemical equations on that page a bit difficult)

If you read through the chemistry of chlorine additions you will see that an SWG has net neutral pH. When chlorine is generated inside the cell, the pH will increase a bit from the formation of hydroxyl ions (OH-). However, all chlorine sanitation and oxidation reactions are acidic (they generate a H+) and so the net effect is no change in pH.

The primary driver of pH rise in ALL pools is the water we we use and the outgassing of CO2. All surface waters and most well waters have carbonate alkalinity in them and it can be quite high. The TA of my fill water is 100-120ppm. When a pool has high TA (anything over 80ppm) and the fill water has high, there is a constant upward drift in pH caused by the outgassing of CO2. You can think of pool water like a can of soda, the liquid inside the soda can will have low pH to start but, once you pop the top and let the bubbles out, the outgassing of CO2 raises pH. Pool water acts in exactly the same way - TA measures, in part, the carbonate alkalinity of the water (how much dissolved CO2 is in it). As the CO2 outgasses from the pool water, the pH rises through a series of equilibrium reactions. This is a well known phenomenon and can be found easily with a search of Wikipedia.

Pool owners experience pH rise when the switch to SWG's NOT because of the SWG but mainly because they were previously using an acidic form of chlorine (dichlor powder and/or trichlor pucks). The acid released from those chlorine sources would slowly reduce TA over time and help suppress the natural pH rise of the water. Then, when the switch is made to net-neutral pH sources of chlorine (SWG's or liquid chlorine), there's a sudden rise in pH because there is no longer anything acidic being added to the pool. As the old adage goes, correlation does not equal causation!

It is simple to prove this and I have done it before - simply put a bubble cover on the pool and stop the outgassing of CO2. When I have a cover on my pool, my pH remains totally stable and barely changes for weeks on end. Without a cover, it will start to rise. And it doesn't matter if my SWG is on or not.

The fix here is simple - lower your TA. I keep my TA between 60-80ppm. If I do that, along with using borates as a high pH buffer, I can easily go 10-14 days without having to add any acid to my pool. Unfortunately, the Industry people will tell you that a TA below 80ppm is BAD for your pool and that is simply wrong too. So the Industry likes to ignore the detailed chemistry only to cause more problems and further lack of understanding.
 
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No.. I started off by directing you to a thread that demonstrates the chemistry behind why SWGs are net neutral in pH and then I explained to you why pH DOES rise in pools - excessive TA. Then I offered you an example from my own pool.

That’s called the scientific method.

You simply offered an explanation based on your experience with no detailed scientific reasoning other than - it’s what I know and what some random industry guy told me .... that’s not science, it’s anecdote.

See the difference??

Now if you don’t like my explanation of TA driving pH, I can also post a bunch of threads by @chem geek (aka, Richard Falk) that describe the detailed chemistry of carbonate alkalinity, CO2 outgassing and pH rise. I did not add those because I figured it would get too in depth and anyone interested can use the Search bar to find them.
 
Thank you everyone!

Yes I have posted before about my ph battle. My husband is the one who normally handles the pool in our old house but is busy running a business so I am trying to get the hang of doing it myself. I just added MA myself for the first time a couple days ago. I have always been intimidated by handling it. Anyway my husband was really against spending money on an expensive kit. I tend to lean towards all of your suggestions. I have a friend who has worked in the pool industry for a long time and he is helping me out by coming over today with his quality test kit and he said he might leave it with me for a bit to use. He is going to a pool trade show in a week or two and said he will grab me a quality test kit for free so I am going to wait for that.

My ph is definitely below 8.2 the color is in the same family as 8.2 but lighter. I know you all hate the pool store but I am confirming my reading of 8 by going there weekly as well.

Everyone keeps saying I need to get my TA down but that is done by adding MA which I am doing daily and it still keeps hanging around 120. We will see what it shows when my friend comes by with his "lab" as he calls it to test my pool today.

I have noticed a couple areas in the pool that look like there is scaling. I have a surface called blue granite so the whiter areas can be easily seen. I am assuming this is due to the high ph battle I keep losing no matter how much acid I add.

I have not drained the pool due to bromine yet. I was told the problem with bromine is that it kills off the chlorine and we are having zero issues with chlorine. I keep having to shut off the production since it keeps creeping over 5. I will have my friend test the bromine levels today as well. I will be having to do a partial drain next week because they are redoing our sunshelf because they left footprints in it. My friend said for pebble tec warranty I need to get my CYA down and the only way to do that is to drain some of the pool so hopefully that will fix itself when they drain for the sunshelf repair.

In regards to water features and ph, I shut off deck jets and sunshelf bubble. We do have a spill over spa but I do not know how to stop it from spilling over aside from putting it in spa mode which shuts off the pool functions so that is not helpful.

I added 8 oz of acid and tested a few hours later and did this three times in one day (24oz total in 5k gallon pool) and ph still stayed at 8 it did not budge at all. Not sure how to win the ph battle at this point...

Pool is over 2 months old at this point. I was told after the first 30-60 days the ph shouldnt be out of control like that. I know I will still have ph rising over the first year but it should not be to the point that I can't get it down after adding that much acid. We add acid daily so we are on top of it but it does nothing.

I know you all hate it but until my friend comes today here are my pool store readings from monday:

chlorine-8 (I shut off the SWG after that)
CYA-70
PH-8
CH-230
pho-100
TA-120

I brought another sample in yesterday and they did not do a full panel test or give me a print out because their machine was down but these are the results I was given:

ph-8
Chlorine-2
TA- she said was around 100

Once I get better test results (my friend is supposed to come today) I will post those as well.
 

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