High PH with Liquid Chlorine

[stdenpi1]

Hello everyone,

Switched over to the BBB method. I have a stenner pump installed now using liquid chlorine. 36k gallon pool in direct sun is really using a lot of chlorine

Anyway...based on my numbers below, I am trying to figure out why my PH keeps rising...

FC:5.5
CC:0
PH 8.0
ALK: 90
CH: between 175 and 200
CYA 60

From what I have read with a CYA of 60 I should maintain between 5 and 7 FC which I do

I have gone thru no less than 8 gallons of Muriatic Acid since May and my PH keeps increasing to 8.0 and above. I try to maintain it around 7.4 - 7.6

Is my CH too low? Is my ALK to high? From everything I have read, my numbers seem to be OK with the exception of CH which should be between 250 and 400 for Gunite.

Any ideas or suggestions, or am I making to much of a big deal of the PH increasing constantly. I live in NY and we did not get a lot of rain the last month so I don't think that's an issue.

Thanks

Pierre

 

[klynne]

Sounds like you are using a lot of Liquid Chlorine, Liquid carries a high ph try adding Borates to your pool. I'm told that it works to reduce your chlorine demand and fight algae by removing most of the carbon dioxide from the pool water. Carbon dioxide is a favorite food source for algae, and occurs in water naturally. Users report that the alkalinity in the water becomes very stable, with less fluctuation, which also lends itself to a more stable pH level. A sparkling look and a silky smooth feel to the water.... perhaps the borates in the pool are reflective, but it is true!

 

[Richard320]

Test your fill water. Odds are, it's high in TA. In my pool, every two inches of water I add requires a quart of MA. I've gotten to the point now where I just add it into the hose stream as I'm filling. Your pool is more than twice the size of mine. I'd be using more than half a gallon a week in my pool was the size of yours, so 8 gallons since May doesn't seem excessive to me.

If you used to use trichlor pucks, you were adding acid constantly without knowing it. Trichlor is very acidic. Now that it's stopped, the pH rises, and you need acid. Go plug your numbers into poolmath and then scroll down to Effects of Adding Chemicals and see what effect an 8 oz trichlor puck has on the chemistry. I bet you'll be surprised.

 

[Donldson]

+1 on testing fill water TA. Mine is around 800, so even a small top off results in a measurable TA increase. Are you adding baking soda to try to keep your TA up? If so then stop and let it drop a bit and see if that helps your pH level out.

From my HTC One via Tapatalk

 

[tim5055]

Sounds like you are using a lot of Liquid Chlorine, Liquid carries a high ph try adding Borates to your pool. I'm told that it works to reduce your chlorine demand and fight algae by removing most of the carbon dioxide from the pool water. Carbon dioxide is a favorite food source for algae, and occurs in water naturally. Users report that the alkalinity in the water becomes very stable, with less fluctuation, which also lends itself to a more stable pH level. A sparkling look and a silky smooth feel to the water.... perhaps the borates in the pool are reflective, but it is true!

just to correct an error here, the use of liquid chlorine is just about pH neutral.

Here is the word from our resident expert....

Just so there is no confusion here, chlorinating liquid or bleach are high in pH and have the pH rise somewhat upon addition to the water, but the consumption/usage of chlorine is acidic so the pH drops back down with the net result that chlorinating liquid or bleach are close to pH neutral (there is some excess lye that causes a pH rise over time, but its low in better sources).

Additionally, borates are not the magic bullet of pool care. If it was we would all have done it long ago.

I might suggest a little reading in Pool School.

 

[YippeeSkippy]

I would also suggest ditching the LaMotte tester because many find it inaccurate and only stick to using your K-2006.

Take your CH up to 300-350. Drop your pH with MA.

Try to determine if you have fountains, jets or anything which is causing the pH to repeatedly rise. If you do and can turn them off check to see if it helps?

 

[stdenpi1]

Thanks for all the responses.

I will definitely test the fill water. I have well water so that could be the cause. I don't have fountains so aerating is also not the issue. I agree that when I changed from Nature 2 with Trichlor that certainly stopped lowering the PH. I test with the Taylor K-2006 test kit.

Thanks

 

[chem geek]

Sounds like you are using a lot of Liquid Chlorine, Liquid carries a high ph try adding Borates to your pool. I'm told that it works to reduce your chlorine demand and fight algae by removing most of the carbon dioxide from the pool water. Carbon dioxide is a favorite food source for algae, and occurs in water naturally. Users report that the alkalinity in the water becomes very stable, with less fluctuation, which also lends itself to a more stable pH level. A sparkling look and a silky smooth feel to the water.... perhaps the borates in the pool are reflective, but it is true!

This is absolutely positively not true. Though all hypochlorite sources of chlorine including chlorinating liquid, bleach, Cal-Hypo, and lithium hypochlorite all raise the pH upon addition, when the chlorine is used/consumed the pH drops back down so overall its close to net pH neutral (except for the small amount of excess lye). See this post for technical details.

As for borates, they do NOT lower the amount of carbon dioxide in the water and carbon dioxide is NOT a limiting algae nutrient in the water -- there is plenty for algae to grow. The limiting nutrients for algae in pool water are phosphates and nitrates and since nitrates are created from chlorine oxidation of ammonia and other nitrogenous organics, it is the phosphates that are the limiting nutrient. However, algae are ultimately limited in their growth rate from sunlight and temperature so one can prevent algae growth maintaining a proper FC/CYA ratio regardless of algae nutrient level. That what the Chlorine / CYA Chart does. I've had over 3000+ ppb phosphates in my pool and others have had 5000 or more (even 30,000 ppb) and all prevented algae growth with chlorine alone. Yes, borates are a mild algaecide (see Table 18 in this link), but not enough to count on and certainly not necessary if one is maintaining the proper FC/CYA ratio. For an explanation of how borates kill insects and that also relates to how algae growth is inhibited, see this video. As for pH control, one should first look at letting the TA drop if their pH tends to rise since that alone may be enough to stabilize the pH since TA is a measure of the over-carbonation of the water and carbon dioxide outgassing causes the pH to rise.