Opinion on using chlorine gas.

SDavisGasMan

In The Industry
May 19, 2020
6
Texas
I Work for a company that uses gas. I'm on my 7th year here and coming up on my 15th year total in the business. I've heard many claims that gas is bad for plaster and have also heard, through the words of customers who have plaster issues, that the gas was the problem. Now I've serviced well over a 1,000 pools with both gas and granular and different ages of plaster as well as different contractors. I don't believe that there is a difference. Chlorine is chlorine but we have lost customers do to other techs telling them that their issue is the gas. I've not once heard how gas damages plaster. Found this forum and want to get opinions.
 
Chlorine gas is very acidic due to how it reacts with the water.

The chlorine from trichlor tabs has the same effect.

Gas can be used safely without damaging anything if it's done correctly.

Ideally, it is added to the water at the same rate that it's being lost so that the level remains constant.

Management of the pH and Total Alkalinity is important to keep the CSI near saturation.

Can you describe how you add the gas and manage the chemistry in general?

How often do you add gas?

How much do you use?

Where do you keep the CSI?
 
Chlorine gas is very acidic due to how it reacts with the water.

The chlorine from trichlor tabs has the same effect.

Gas can be used safely without damaging anything if it's done correctly.

Ideally, it is added to the water at the same rate that it's being lost so that the level remains constant.

Management of the pH and Total Alkalinity is important to keep the CSI near saturation.

Can you describe how you add the gas and manage the chemistry in general?

How often do you add gas?

How much do you use?

Where do you keep the CSI?
Depending on the pool it's normally a 4lbs shot. There is no gauge to determine other than the freezing of the gas into a solid which comes out to about 4lbs. Most pools at this time are every other week. Leaky pools and dirty require every week. We try to maintain cl level at a 4 to 4+ ..PH at 8.0 and Alk at 120-140 and Stb at 60-100. I do 45 to 50 pools a day.
 
Depending on the pool it's normally a 4lbs shot. There is no gauge to determine other than the freezing of the gas into a solid which comes out to about 4lbs. Most pools at this time are every other week. Leaky pools and dirty require every week. We try to maintain cl level at a 4 to 4+ ..PH at 8.0 and Alk at 120-140 and Stb at 60-100. I do 45 to 50 pools a day.
Also unless the ph and alk are alreasy high we add sesqui sodium carbonate on each shot.
 
Dosing every other week using an indeterminate amount of gas is going to have the chemistry go all over the place.

The chlorine might be anywhere from 20 to 100.

The pH will go down quite a bit due to the acidity of the gas.

In my opinion, dosing every two weeks or even weekly is not a good method for chemistry management.

You should set up a few test pools where you monitor the chemistry continuously so that you can see what happens to the chemistry between visits, especially immediately after the gas injection.
 
Dosing every other week using an indeterminate amount of gas is going to have the chemistry go all over the place.

The chlorine might be anywhere from 20 to 100.

The pH will go down quite a bit due to the acidity of the gas.

In my opinion, dosing every two weeks or even weekly is not a good method for chemistry management.

You should set up a few test pools where you monitor the chemistry continuously so that you can see what happens to the chemistry between visits, especially immediately after the gas injection.
Most pools barely last every other week. They will go down to a 2-3 so we have to add to maintain. Right now every other weekers are hard to come by. Some pools are every week but they're usually leakers or have a lot of swimming. The winter time some pools could go a couple months. Ph and alk usually remain constant from week to week. Some will drop to 7.6-7.8. And 100-110. As long as we're adding the sodium bicarbonate balance usually stays consistant. My main reason for the post...maybe I didn't state... was the idea of gas being detrimental to the plaster. Having worked for both gas and non gas I've seen pools in poor states regardless. We tend to loose some customers from time to time though do to a customer being told that gas does damage plaster and it's annoying.
 
Most pools barely last every other week. They will go down to a 2-3 so we have to add to maintain. Right now every other weekers are hard to come by. Some pools are every week but they're usually leakers or have a lot of swimming. The winter time some pools could go a couple months. Ph and alk usually remain constant from week to week. Some will drop to 7.6-7.8. And 100-110. As long as we're adding the sodium bicarbonate balance usually stays consistant. My main reason for the post...maybe I didn't state... was the idea of gas being detrimental to the plaster. Having worked for both gas and non gas I've seen pools in poor states regardless. We tend to loose some customers from time to time though do to a customer being told that gas does damage plaster and it's annoying.
Also the bottle is only capable of putting out around 4lbs before it solidifies and stops putting out gas.
 
The chlorine gas isn't specifically a problem for plaster.

However, the method being used is not going to to give you very good chemistry.

Can you post actual chemistry results from a typical pool on a daily basis for a season including all readings and water temperature and CSI?
 
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