Liquid Chlorine and high PH

classj

New member
Apr 22, 2019
4
NJ
I am planning to open the pool for the season in the next week and could use some chemistry advise on what to improve over last season.

I am heading into my third season as a pool owner and after fighting high CYA on tablets, with the help of TFP, at the start of last season I switched to liquid chlorine (12.5% from leslies). I drained my pool down 50% and brought my CYA to around 70 at the start of last summer. I started last season with a TA of 110. CH around 280. Ph of 7.4.

I maintained FC at 4 to 5 ppm all season using fresh gallons of chlorine. I shock every couple weeks using cal hypo from leslies or in the swim. The issue was PH seemed to float up to 7.8 very often and 8.0 if left un-adjusted for a week. I had to lower PH using dry acid weekly. This would last a couple days. Then PH would rise from the chlorine. The acid additions led to the TA dropping to as low as 50 during the season so I would lower the PH with dry acid to 7.4, then the following day raise the TA using baking soda. Within 24 hours after that I would be back to 7.8 ph but with the higher TA.

The water usually felt less comfortable than it had when the pool was on tablets. I assumed it was the higher PH and lower TA at times. When the PH got too high I had metal staining on my white steps so I started using jacks blue stuff to keep that at bay. I have domestic water but it is sourced from wells in my town.

I felt like I was chasing my tail all season with 4 cup measures of dry acid and boxes of baking soda. I have a Taylor K-2006 kit with reagents that are not expired. I test PH and FC every 24 to 48 hours max. I closed the pool with a TA of 70 if I was lucky and a PH of 7.6.

I know that liquid chlorine is supposed to only temporarily raise PH but it did not seem to the be the case for me. I do keep one of the return jets pointed at the surface for water movement. Could that alone be the cause of the high PH?

A friend suggested to add borax to the pool but I have not researched yet.

I hope to get my CYA down to closer to 50 at the start of this season but other than that any suggestions from the TFP forum would be greatly appreciated!
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,434
Laughlin, NV
Welcome to the forum!
Liquid chlorine does not raise the pH in your pool overall. When you used tablets, they are very acidic, so that kept your pH down. Probably too low if your water was uncomfortable.
Your pH should stabilize once your TA gets to equilibrium. Do you have a lot of aeration? What is the pH and TA of your fill water.

You should be using muriatic acid, not dry acid. Dry acid adds sulfates which are not good for your pool equipment.
Only lower your pH to 7.6 when it gets to 8. Only concern yourself with TA when it drops below 50 ppm.

There should be NO reason to add Cal Hypo as a 'shock' when following TFP processes.

I suggest you read ABC's of Pool Water Chemistry and consider reviewing the entire Pool School eBook.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter

classj

New member
Apr 22, 2019
4
NJ
Welcome to the forum!
Liquid chlorine does not raise the pH in your pool overall. When you used tablets, they are very acidic, so that kept your pH down. Probably too low if your water was uncomfortable.
Your pH should stabilize once your TA gets to equilibrium. Do you have a lot of aeration? What is the pH and TA of your fill water.

You should be using muriatic acid, not dry acid. Dry acid adds sulfates which are not good for your pool equipment.
Only lower your pH to 7.6 when it gets to 8. Only concern yourself with TA when it drops below 50 ppm.

There should be NO reason to add Cal Hypo as a 'shock' when following TFP processes.

I suggest you read ABC's of Pool Water Chemistry and consider reviewing the entire Pool School eBook.
Thanks! I have the strongest return jet pointed at the surface to help with skimming and I run the pool 10 hours when the summer is hottest. 8 hours normally. Should I direct the jet into the deep end instead?

I can switch to muriatic acid if it is better. Dry acid was just easier to transport and handle. I will research the sulfate issue.

Is it normal to have to keep pH at the higher range with a liquid chlorinated pool? It just seemed to want to sit at 7.8. When the pH was high, the the TA was low was when the water felt the most uncomfortable.
 

classj

New member
Apr 22, 2019
4
NJ
Regarding shocking. Is the preferred method to use only liquid chlorine?

I don't shock on a schedule but we had the wettest summer on record last year in NJ with something like 50" of rain from May to early October. It seemed like I was shocking a couple times a month as a precautionary measure
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,434
Laughlin, NV
TFP does not 'shock'. Maintain your FC based on your CYA using FC/CYA Chart.

Water naturally wishes to sit at a pH of 7.8 or so. Are you sure the pH was high when you used tablets? It is not normal to have high pH and low TA, naturally.
 

classj

New member
Apr 22, 2019
4
NJ
TFP does not 'shock'. Maintain your FC based on your CYA using FC/CYA Chart.

Water naturally wishes to sit at a pH of 7.8 or so. Are you sure the pH was high when you used tablets? It is not normal to have high pH and low TA, naturally.
My fill water has a TA of about 100 and a PH of 7.8.

When I used tablets last in 2017 I would just toss in some baking soda once in a while to keep the pH around 7.4 to 7.6. I also had the jets pointing upward to help keep the pH high since the tablets would pull it down. The high jets also help with skimming.

Last year in 2018 I used liquid chlorine and the pH seemed to want to sit at 7.8 to 8.0. Weekly I would throw some dry acid in to bring it down to 7.4 to 7.6 but it would float back up quickly. The repeated acid doses lowered my TA over time from 110 to 50. I raised it to 70 before closing.

Is the thought that I should try to keep the TA in the 70-100 range and target a pH of 7.8?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,434
Laughlin, NV
Keep the ph around 7.8 and let TA be what it is. Your fill water will push your TA up and your ph will rise. Just do not drop ph below 7.6 when it gets to 8.
 

needsajet

TFP Expert
LifeTime Supporter
Jan 4, 2016
4,698
Sydney, NSW, Australia
Welcome to TFP! Good to have you here :)

pH 7.8 is within the normal accepted range. No need to adjust unless it goes higher.

If the return jet aim is doing the skimming job for you, I would leave it as-is. Yes, it will have a slight effect on pH, but it isn't much, and skimming debris is like the first line of defense against pool maintenance work!
 
  • Like
Reactions: splashpad