pH will not go down with Muriatic Acid

klroahs

Active member
Jun 7, 2010
33
Huntsville, AL
Hello,

I am a new pool owner with a pebble sheen surface. I have been using the Muriatic acid recommended by the pool calculator, however, it does not seem to have any affect to the pH 4 or 24 hours after the fact.

It is 30,000 gallons salt water pool with the following values from the pool store today:

.5 Free Chlorine
.5 Total Chlorine -- these values have gone down even though I have raised the percentage on my SWG up since my last visit
pH 7.9
Ca Hardness: 191
TA: 100
Cyanuric Acid: 40

Any tips on how to get my pH down? Is Muratic acid not as effective as the pH down the pool store wants to sell me?

Thanks for any help you can give me!
 

257WbyMag

TFP Expert
LifeTime Supporter
Feb 23, 2008
5,061
Denton, TX
Welcome to TFP!

If your plaster is less than one year old, you will find that your pH climbs very quickly. It will do this over the first year as the surface cures. Couple this with the fact that you are also running a SWCG, your pH will climb doubly quickly with the plaster curing effect.

Muriatic acid does lower your pH, but it will only do so temporarily. You may need to add acid, and a lot of it, every day.

ETA: I also noticed that your chlorine is very low. You need to get that up and soon or you are likely going to end up with algae. With your CYA of 40, your FC needs to be a minimum of 3 ppm with 5 being the target for day to day.

Have you looked at Pool School? It's the big button on the top right of every page. There is valuable information in there.
 

klroahs

Active member
Jun 7, 2010
33
Huntsville, AL
Thanks, until now, most of my numbers have been in the recommended ranges at the pool store(s) I have taken sample to. From your response, I am unsure if the Muratic solution is the way to go, what is the permanent solution to keeping acid down, or is this just going to be an ongoing battle for the first year or so? If so, should I stick with buying Muriatic acid?

I am confused about my FC, as I have been raising my SWG percentage. I have read through the pool school, but it is a lot of information overload. I am not sure what I need to hit first :(.

Thanks for the quick response!
 

JasonLion

TFP Expert
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May 7, 2007
37,880
Silver Spring, MD
For the first three or four weeks after fresh plaster is applied, the PH tends to go up very rapidly. It will then continue to go up much more slowly for up to a year.

Muriatic acid is the best thing to use to keep the PH under control. You want to try to keep the PH under 8.0 at all times. That usually means daily acid additions for the first three or four weeks.
 

duraleigh

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Apr 1, 2007
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Sebring, Florida
I am confused about my FC, as I have been raising my SWG percentage. I have read through the pool school, but it is a lot of information overload. I am not sure what I need to hit first .
Stay focused on correcting one issue at a time and the overload will become very manageable.

Get your pH management in check. Are you OK with the answers on your pH above? If so, post back and we'll move on to the next step which will be managing your chlorine.
 

zea3

Mod Squad
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Jul 10, 2009
11,067
Houston, Texas
As has been said by the other 3 responses, you will need to test and adjust the pH daily for now. You also need a high quality test kit so you can test the pH and FC (free chlorine) daily. The best available kits are the TF100 and the Taylor K2006.

Since you are running a SWG (salt water chlorine generator) you need to raise the CYA to 70.

Once chlorine levels are established, SWGs do a great job at keeping the FC at a consistent level. However they do not crank out chlorine quickly. It is best to establish FC at the level recommended for your pool. According to the Pool Calculator your FC should be between 2-7. You want to keep the FC at the high end of the range to prevent algae. Boost your FC with liquid chlorine until your SWG has a chance to catch up.
 

hawkeyes

LifeTime Supporter
Mar 25, 2010
100
Dallas, TX
I have a pebble surface and SWG as well....I add anywhere from 20-40 oz of acid every other day due to rising pH and have been doing this for 3 months now. Since getting my TA down a bit (it was running at 100 and now it's usually closer to 80) the acid additions have been a bit lower---but not considerably. I, too, am hoping after the first year this issue gets better!
:wink:
 

klroahs

Active member
Jun 7, 2010
33
Huntsville, AL
duraleigh said:
Are you OK with the answers on your pH above? If so, post back and we'll move on to the next step which will be managing your chlorine.
I am OK with the pH issue, having no frame of reference confused me :). My pool installer guessed I had been putting about a gallon per week, which I have not been doing until now.

My installer (who lives where he knows I won't be able to buy supplies from him :)) said they recommend 1 - 1.5 for Chlorine, which does not seem to match what everyone is saying here (or on Pool School) since the SWG is always generating Chlorine. He also said that I might be having problems keeping it down b/c of the Phosphates. Which I seem to recall reading on this site to ignore if my Chlorine is kept in check (but cannot seem to find now).

Maybe I am answering my own question about the differences in numbers. :)

I do appreciate all of the help. BTW, I have a kit that I purchased from here.

I have gotten 3 different numbers from 3 different pool stores concerning my CYA 40, 50, & 60....go figure. I don't know who to trust
 

frustratedpoolmom

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May 20, 2007
12,177
SWSuburban Chicago, IL
Trust your own testing on CYA.
Industry folk constantly parrot "1-3" FC and completely ignore the FC to CYA relationship. Always follow the CYA chart and you'll be fine, and yes, if you maintain the levels we recommend you can ignore phosphates. Phosphates are algae food, but if you maintain the proper FC level they are essentially irrelevant.
 

svenpup

LifeTime Supporter
Nov 18, 2009
835
Sacramento, CA
klroahs said:
...said they recommend 1 - 1.5 for Chlorine, which does not seem to match what everyone is saying here (or on Pool School) since the SWG is always generating Chlorine.
Use the recommended level for SWG with your CYA level in the Chlorine/CYA chart (link in my signature...Looks like 3-4ppm for now until you get your CYA up a little)


klroahs said:
He also said that I might be having problems keeping it down b/c of the Phosphates. Which I seem to recall reading on this site to ignore if my Chlorine is kept in check (but cannot seem to find now).
Phosphates are irrelevant if you keep you FC in range. If you think of phosphates as food for algae, it doesn't matter how much food is available if there aren't any algae alive to consume it.


klroahs said:
Maybe I am answering my own question about the differences in numbers. :)
I do appreciate all of the help. BTW, I have a kit that I purchased from here.
I have gotten 3 different numbers from 3 different pool stores concerning my CYA 40, 50, & 60....go figure. I don't know who to trust
It sounds like you have the TF-100 from TFTestKits. Trust your own test.
 

klroahs

Active member
Jun 7, 2010
33
Huntsville, AL
OK, I think if I am reading your posts and pool school, what I think I should do now is get my FC up by using the pool calculator to tell me how much liquid bleach to add to reach the desired shock level, and shock it according the the process at pool-school/shocking_your_pool.

Or should I instead just add enough to get it to 3-4ppm and shock it only if the overnight FC test shows that I need to shock?
 

JasonLion

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May 7, 2007
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Silver Spring, MD
I suggest raising FC to around 8 this evening, wait an hour, if it is still around 8 after an hour, do an overnight FC loss test. If it has gone down significantly start shocking the pool.
 

klroahs

Active member
Jun 7, 2010
33
Huntsville, AL
JasonLion said:
I suggest raising FC to around 8 this evening, wait an hour, if it is still around 8 after an hour, do an overnight FC loss test. If it has gone down significantly start shocking the pool.
OK, forgive me for what me the obvious, by rasing to 8, I assume you mean to use the pool calculator to tell me how much bleach to add, and add it :).

Just making sure
 

primetime

LifeTime Supporter
Jul 28, 2008
58
Sinking Spring, PA
My pool was new last June and I also have pebble sheen, SWG, and 33,000 gallons so our pools are very similar. Here is what worked for me last year and what I am doing now. It is based on what I learned here but I also add another product. I am very happy with my pool and the water quality. TFP is the way to go! BTW I use the TF-100 test kit and the Taylor Salt Testing Kit. I do not recommend the salt test strips. They are a pain. I also get my water tested once a month at Leslie's because they use the Taylor reagents (which are similar to the TF-100) and their measurements are very close to mine. It gives me peace of mind. My pool builder uses some computerized testing system with little vials, but it is way off sometimes so I do not trust it.

When my pool was first filled, my pH and alkalinity were both sky high. You are in a little better shape then me because my alkalinity was 180 to start. I used the dry acid at first, but for me the muriatic acid is easier and cheaper (just don't breath it in) to use and is what I use now. I buy it at the local ACE Hardware Store and Home Depot. At my Home Depot they keep it at different spots depending on the season so you might have to ask for it.

As everyone noted above, the pH will continue to go up for the first few weeks. You will need to control it almost daily. What I found is that after about three weeks, (and, after I got my water locked in very close to the recommended level in Pool School for salt water pools), I only needed to add about a quart of muriatic acid every week to keep my pH around 7.5 to 7.8. The rest stayed pretty much right in line. I think the key is to get the alkalinity in the 80 -90 range. For some reason that seems to help the pH.

Here is where I tried to keep my readings: FC 5.0-6.0, ALK 80-90, pH 7.5 - 7.8, CYA 60-70 (now I notice that pool school is recommending CYA a little higher, but 60-70 works for me)

All the pool stores and all the other people who have salt water pools will tell you to keep your FC at 1.0. Don't believe them. Some of the folks I know who keep it at 1.0 have had algae. Plus, if you get a high bather load on a hot sunny day you can quickly run your FC to zero! I found the people at pool stores are not very knowledgeable about salt water pools so you really cannot trust them. I would follow the advice here instead.

I use one other product that I really like. It is called Salt Water Magic by Natural Chemistry. It will cost you $45 per month because you will need one and a half kits per month. I really notice a difference in my water with it and it will keep your phosphates at zero if you use it every month. Based on feedback here at TFP there is no need to worry about phophates with FC at 5.0 -6.0, but I like knowing it is at zero anyway!!!

This year I added borates to my pool. Actually just this past weekend. So far my pH has stayed at 7.5 (but I only added them on Saturday) I noticed a slight improvement in my water, but my water already sparkled due to the Salt Water Magic and keeping my water properly balanced.

Please let me know if there is anything I can help you with.
 

klroahs

Active member
Jun 7, 2010
33
Huntsville, AL
Thanks for the helpful replies!!!

I must admit, I have (way) overshot the 8 FC I was told to target, I think it is 11.5 (- .5 for CC is that how that works).

I used the pool calculator, but I must not have the right number of gallons. These too have been estimates, but I now think the 30,000 I used is too much b/c the chlorine I added really was high. Could it be that since I only waited an hour(ish) it did not have time to mix well? I took two samples from different parts of the pool.

However, when adding the muriatic acid with the same gallons, I see little or no change?

Do I just let the chlorine settle itself down, or is there something I should do to correct it? I am sorry for this, I am trying to get my numbers closer to what you have here than the stores' printouts.

Luckily, I measured the final FC after dark, so I will still see if it drops overnight.
 

klroahs

Active member
Jun 7, 2010
33
Huntsville, AL
primetime said:
Here is where I tried to keep my readings: FC 5.0-6.0, ALK 80-90, pH 7.5 - 7.8, CYA 60-70 (now I notice that pool school is recommending CYA a little higher, but 60-70 works for me)
LOL, primetime, our pools are very similar, my pools has been estimated from 28,000 - 34,000, from my earlier post you can see I don't know what to believe any more. I don't feel like breaking out the integral calculus to be sure :).

I am curious if you have any problem with Ca Hardness, as that is one of the items on the pebble sheen site for pool care, but I might be getting off topic, but I might have left topic when I started down the chlorine questioning....
 

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