Gas Chlorine?

RMcGirr83

Gold Supporter
Nov 19, 2018
970
Tuscola, TX
What in the heck is "Gas Chlorine". Saw this in one of my spam facebook group things
"Pool cleaning service/ exclusive gas chlorine!! We offer a monthly pool cleaning service and an exclusive gas chlorine service."
Is this like magic unicorn pixie dust?
 

JamesW

TFP Expert
Mar 2, 2011
28,257
Gas chlorine is chlorine gas that comes in a tank under pressure like any other gas sold under pressure (carbon dioxide, helium, argon, nitrogen, hydrogen, propane etc.)

It can be applied to a pool, but it's dangerous and it is very acidic.

Some commercial and governmental organizations use gas chlorine in water treatment.

Some companies treat residential pools with gas chlorine, but they require special permits and licenses.

When using gas chlorine, you need to offset the acidity with something to raise the pH and TA.

Unless they're coming every day, they will have to overtreat to try to make the chlorine last until they return.

I would not use the service.
 
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Donldson

TFP Expert
LifeTime Supporter
Jun 12, 2009
5,151
NW Ohio
A gas truck, similar to a propane truck, pulls up out front of your house. The tech drags a hose out back and drops it in to the deep end. Then turn it on and bubbles start to float to the top. This is the chlorine gas, most of which is absorbed in to the water. They run that for about 15 minutes, then wind the hose up and leave.

I disagree with James, while the service itself may be overpriced and underwhelming the introduction of chlorine gas is by its very nature the most pure way to introduce chlorine. Saying that they will "overtreat" the pool is an odd stance, since it is doubtful they would raise the FC over SLAM level. The acidity is a concern, but that can easily be offset by running a TA in the 150-200 range.

If a company offered to dose my pool once a week and do nothing else to it, and it was cheaper than using liquid chlorine, I would do it. Odds are that they are much more costly than that and want to do other maintenance to your water that you really would rather them not do.
 
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JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
18,610
Tucson, AZ
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Pima Chemical Company around here does gas injection. The process requires high CYA (typically around 120ppm) and then gas injection for an FC up to 14ppm. They also add bicarb or soda ash to offset the pH drop. If you follow that protocol, then the FC can last about 7 days before getting critically low. The service runs weekly. It is definitely more expensive than dosing LC yourself but many people like the convenience.
 

JamesW

TFP Expert
Mar 2, 2011
28,257
Phoenix and Tucson have some of the highest UV in the country. How is 14 ppm going to last a week?

You would need to lose less than 1 ppm per day to remain above the minimum fc for a CYA of 120.

That's not realistic.

Even if you dose up to SLAM level, the initial losses will be quite high due to the high fc/CYA level

Has anyone done any quality control on this?

The dosing has to be done very carefully to be right.

Seems like a bad idea to me.
 

PoolGate

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Jun 7, 2017
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Damascus, MD
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Jandy Aquapure 1400
If you are interested in gas chlorine, get a saltwater chlorine generator. It creates chlorine gas which is absorbed by the water. Best of all worlds!
 
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JoyfulNoise

TFP Expert
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May 23, 2015
18,610
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Phoenix and Tucson have some of the highest UV in the country. How is 14 ppm going to last a week?

You would need to lose less than 1 ppm per day to remain above the minimum fc for a CYA of 120.

That's not realistic.

Even if you dose up to SLAM level, the initial losses will be quite high due to the high fc/CYA level

Has anyone done any quality control on this?

The dosing has to be done very carefully to be right.

Seems like a bad idea to me.

I never said it was realistic ?

.... but, believe it or not, I have measured summertime 24-hour loss rates of FC in my own pool around 1ppm when my CYA is high and my phosphates are low. So it’s possible under some very strict circumstances. But I agree that for the standard pool owner, it’s a terrible way to run a pool.

An SWG is definitely a better & safer idea.
 

QueHales

Member
Nov 24, 2017
11
Tucson, AZ
I ran a gas chlorine operation for over 30 years. Just a few points:
  • The hose is run from deck to disperser on the bottom of the pool, not from the truck. The cylinders are ca. 20 pounds empty and 50 pounds full, and are carried to poolside.
  • The dose in the desert southwest is generally around 2 pounds chlorine gas per 20000 gallons of pool water, with a 100 ppm CyA level.
  • The weekly chlorine readings when doing this are approximately 3 ppm after one week since injection.
  • The TA is generally run 120-140 if the borate level is around 50.
  • The method was originated by Pool Chlor in the 1950s. They were some of the first users of cyanuric acid, and were the originators of borax in swimming pools.
  • In its heyday, the National Association of Gas Chlorinators (of which I am a past president) had some 50 member companies nationwide, which did not include the California Chemical (Sparkle) system, which did not participate. There were easily over 100000 residential pools nationwide being treated this way.
  • Membership dropped off around the turn of the century as placarding, commercial driver's licenses, hazmat endorsements, PSM/RMP programs, etc. made regulatory compliance more and more difficult.
  • After heavy regulation by OSHA, DOT and EPA for 3ish decades, Homeland Security jumped on the regulatory bandwagon. It got to the point where the regulatory burden got so ridiculous that as far as I know the California Chemical people are the only ones still trying it...
  • Like virtually ANY form of chlorination, there are those who do things right, and there are those who cut corners. And there are obviously right and wrong ways of doing things...
 

RMcGirr83

Gold Supporter
Nov 19, 2018
970
Tuscola, TX
Thank you all for the posts. I never heard of it and thought it a bit odd. You read, every now and then, about chlorine gas escaping from a train wreck and causing all sorts of issues. Just didn't think it would be very logical in this day and age.
If you are interested in gas chlorine, get a saltwater chlorine generator.
Wasn't interested in the gas chlorine but am considering getting a SWG just so I don't have to tote chlorine bottles around.
 

Rattus Suffocatus

Silver Supporter
Jun 5, 2019
1,445
Corona de Tucson, AZ
I never said it was realistic ?

.... but, believe it or not, I have measured summertime 24-hour loss rates of FC in my own pool around 1ppm when my CYA is high and my phosphates are low. So it’s possible under some very strict circumstances. But I agree that for the standard pool owner, it’s a terrible way to run a pool.

An SWG is definitely a better & safer idea.
My across the street neighbor uses Arizona Pima Chemical and I have to admit when I saw the truck pull up with multiple tanks of Chlorine gas, I about freaked out.

So far their pool looks okay. I've been meaning to ask my neighbor if I can run some water samples because I can't help but be curious about it. His pool is less than a year old (I live in a new construction neighborhood), so we will see what happens over time next year. I actually did calculate out the cost.. and they are actually quite cheap. They might be the cheapest service in Tucson. They would probably be slightly cheaper than the liquid chlorine is from E-Konomy here.... I still think I'll eventually do the SWCG... in the spring.... It makes me nervous to have a truck full of Cl gas near my house on the street the way the people in Tuscon drive (which is certifiably nutty insane) as it is.

It might be really doable if they did a twice a week.. but I doubt if they offer that....
 

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JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
18,610
Tucson, AZ
Pool Size
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Chlorine
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Honestly, chlorine gas is only dangerous in a confined space. In an outdoor setting, it will dilute with air fairly rapidly and react so quickly that it doesn’t linger for long. The real danger comes from the rapid oxidation caused by chlorine potentially igniting an explosive or flammable material.

There’s a reason why chlorine gas was never used as a chemical warfare agent - it’s too inefficient and unpredictable.
 
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Etchase

Active member
May 22, 2019
34
Hawaii
Don’t some large commercial pools operate onsite chlorine gas generators, and then inject the gas into the returns? I believe there is some energy savings utilizing this method over traditional SWG, but I’m not sure this is the reason they are utilized. This particular pool had lots of fountains and waterfalls, so I believe they still had to add acid.
 

CaveDiver1932

Well-known member
Mar 2, 2014
110
Dallas
Honestly, chlorine gas is only dangerous in a confined space. In an outdoor setting, it will dilute with air fairly rapidly and react so quickly that it doesn’t linger for long. The real danger comes from the rapid oxidation caused by chlorine potentially igniting an explosive or flammable material.

There’s a reason why chlorine gas was never used as a chemical warfare agent - it’s too inefficient and unpredictable.
Yea never go down into a tunnel in a sewage treatment plant without testing first in some fashion. Closed area will kill someone fast. One of few things that stuck with me as we had requirement when I was engineering school to tour a treatment facility. Yea, it was a requirement even though had nothing to do with the engineering field I was studying.
 

mguzzy

Gold Supporter
I ran a gas chlorine operation for over 30 years. Just a few points:...
When I was a kid I remember the pool service my parents used in the mid 70's was like that. The pool guy was a grumpy old dude that seemed to partake of the chemicals he dispatched. He had a tank of chlorine gas and threw this thing in the bottom of the deep end of the pool that looked like parts that were ripped from a old gas stove. He turned the knob on the tank and started a stop watch. The chlorine gas bubbled up from the bottom and dissolved by the time it got to the surface where there was only surface turbulence from the moving water. When the appointed time came he shut off the knob and gave me a crusty wink... "no swimming for 6hrs" he grumbled and he lumbered off with his tank. I didn't think that kind of pool service existed anymore.

[repost.. it seemed appropriate here]
 

jseyfert3

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Oct 20, 2017
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Don’t some large commercial pools operate onsite chlorine gas generators, and then inject the gas into the returns? I believe there is some energy savings utilizing this method over traditional SWG, but I’m not sure this is the reason they are utilized. This particular pool had lots of fountains and waterfalls, so I believe they still had to add acid.
I was under the impression they just buy and store bottles of compressed chlorine gas. I don't believe they generate it on site. Basically it's like the chlorine gas injection service only they keep the bottles on site and inject it continuously and slowly instead of a "shock" treatment.
 
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wogster

In The Industry
Apr 30, 2018
161
Toronto, Ontario, Canada
Don’t some large commercial pools operate onsite chlorine gas generators, and then inject the gas into the returns? I believe there is some energy savings utilizing this method over traditional SWG, but I’m not sure this is the reason they are utilized. This particular pool had lots of fountains and waterfalls, so I believe they still had to add acid.

Commercial operators have several options, one would be a CL gas injection, another would be a SWCG, yeah it may be the size of a '69 Buick, but still it is possible. Either can be set up to feed at a constant rate, or automated using an ORP based system that turns on/off the chlorine feed.
 
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Motozoic

Well-known member
Oct 30, 2018
68
Tucson, AZ
I'm assuming that procuring a tank of compressed chlorine gas and plumbing it into a residential pool filtration system using a computer controlled release valve would be a bit unsafe? My neighbor has a chlorine gas service and the water seems overchlorinated.
 

chiefwej

LifeTime Supporter
TFP Guide
Jun 12, 2011
3,735
Tucson
I'm assuming that procuring a tank of compressed chlorine gas and plumbing it into a residential pool filtration system using a computer controlled release valve would be a bit unsafe? My neighbor has a chlorine gas service and the water seems overchlorinated.
Why not just make your own chlorine gas and control its injection? That’s exactly what a SWG does.
 

red-beard

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May 27, 2019
1,395
Houston, TX
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In my days working at a very old YMCA in the 1980's, they used chlorine gas to chlorinate the indoor pool. They also used DE for the filter. All of the equipment dated from 1910-1920. I do remember we tested the water 3 times a day, but just Chlorine and pH.
This YMCA was one of the originals, which had "rooms" for rent.
 

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