Facts and opinions please. Salt vs Chlorine?

mguzzy

Well-known member
Jul 8, 2015
919
OV, CA
1: "All the pool water" is not run through an SWG cell. A small fraction is and is chlorinated and is returned to the pool where it is diluted. Really this is the same thing that happens when chlorine is introduced via a jug of liquid chlorine. In fact if the "super chlorination" thing is true then liquid chlorine would be better since it actually chlorinates the water it touches more than an SWG cell which really only raises the FC of the water flowing through it by a few PPM. For example: a T-15 cell produces 1.45 pounds of chlorine in 24 hours. That would be roughly 1 ounce per hour. 0.016 ounces per minute. The minimum flow rate for that cell is 11 GPM. So this means that at the absolute slowest operational speed you will see 11 ppm FC introduced to the water flowing through. That's not that much, really. A pool with 80 CYA and manually chlorinating might see the entire water reach that level for extended periods of time, not just a few seconds through the pipes and then diluted with the rest of the water.

2: This is the same argument made by UV advocates and falls short the same way. As mentioned above this only happens with the water inside the cell as it passes it is of little benefit when CC exists in the bulk water. CC is broken down quite readily by sunlight and maintaining proper chlorine levels and thus should be minimal in any TFPC pool, not just SWG ones.

3: The CYA is different because SWG's produce chlorine slower and more regularly and thus benefit from having more protection from sunlight.

4: "I was told this so I will repeat it as fact" is not a very good habit to get in to. Anyway, if it is true then the same effect could be accomplished by raising the salt level of a manually chlorinated pool.

5: Your claim was that, "The electrolysis process within the cell has a some beneficial side effects that you don't get by just dumping liquid CL in the water. " Point 5 is accurate but irrelevant to that claim.


As I have said and will continue to say, there are enough positive aspects to an SWG for them to be well respected pieces of equipment around here. They don't need misleading comments about their ability. Chlorine is chlorine.
1) in my pool ALL the water goes through the cell. there is no bypass. Then it splits to spa and pool. Yes the super chlorination effect only happens when the chlorination is doing it thing. Still all the water goes through the cell and there is a greater chance of the super chlorination effect at any given time during the cells cycle.
2) Maybe.. I'm speaking of SWGs.. in a pool chlorinated with liquid chlorine the CCs are left to degrade over time.
3) There you go!
4) I am a physicist by training.. spent much time with chemists.. If you require a peer reviewed article I'm sure I can dig one up to provide a proper citation. I figured a discussion of molecular reactions involved was beyond the scope of this thread.
5) It is not irrelevant to the post I was commenting on.. The biggest difference between the delivery of chlorine to the pool between and a SWG, is I don't have to get the chlorine from the store and all the overhead that is involved with it, gas, time, effort.
Love the debate.. I'm sure the OP.. got a lot more information than intended.
 
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duraleigh

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I'm with dnldson. There is NO measurable distinctive benefits to chlorinating by using electrolysis as opposed to pouring in liquid chlorine (bleach).

The key word being "measurable".

OP, you are correct........a discussion of molecular reactions is beyond the scope of this thread and, for that matter, the scope of TFP.

TFP's target audience is people who want to carefully test and manage their own pool water and then go swimming in a crystal clear pool. Debating the dubious benefit of an unmeasurable process is simply not up on the radar.
 

madtv126

Gold Supporter
Jul 30, 2018
90
Fort Mill, SC
As a non chemist, non physicist, but maybe a psycho (when it comes to my pool) :cool:. I like my SWCG and find the beauty of it is that I don't have to worry about adding chlorine via jugs on a daily basis especially in the heat of the summer.

But taking care of a pool does require weekly testing and at least daily observation no matter what how the pool is chlorinated (no pucks please). I suggest looking around the forums a little more if you are going to go the TFP way. (which is the only way for me).

I have many neighbors with pools that use services, or the pool store and spend a ton of money on chemicals or weekly cleaning. My one neighbor has a pool that has 300 CYA in and can't understand why he keeps getting algae even though he shocks everytime he has people over swimming., but that is another thread I am sure.

As for SWCG or chlorine, yes there are upfront costs to consider and based on what I understand it is basically a push on the cost overall, but it might not be on the work. I spend about an hour of actual time per week on my pool not including the zen like time I get when I brush or vacuum the pool for purposes of relaxation. (see sounds psychotic).

TLDR: SWCG is what I like but ultimately its a personal preference because you can add salt for water feel.
 

Cody

Bronze Supporter
Aug 17, 2014
209
Prosper, TX
I'm with dnldson. There is NO measurable distinctive benefits to chlorinating by using electrolysis as opposed to pouring in liquid chlorine (bleach).

The key word being "measurable".

OP, you are correct........a discussion of molecular reactions is beyond the scope of this thread and, for that matter, the scope of TFP.

TFP's target audience is people who want to carefully test and manage their own pool water and then go swimming in a crystal clear pool. Debating the dubious benefit of an unmeasurable process is simply not up on the radar.

I posted on another thread as well, but this fits here....I'm having SWG installed today, so I referenced the CYA chart on this site. I noticed that the FC needed for SWCG is less than the FC needed for a pool without SWG.....why is this?

I'm going to be shooting for CYA of 70....i assumed that would have me at a minimum FC of about 5....but according to the chart (below), it's only 3. Why the difference when using SWG?


Non-SWCG Pools

SWCG Pools

CYA (Stabilizer)Minimum FCTarget FCSLAM FC
60*3424
703528
804631
 

Jeff J.

Active member
Aug 6, 2019
33
Staten Island NY
As a non chemist, non physicist, but maybe a psycho (when it comes to my pool) :cool:. I like my SWCG and find the beauty of it is that I don't have to worry about adding chlorine via jugs on a daily basis especially in the heat of the summer.

But taking care of a pool does require weekly testing and at least daily observation no matter what how the pool is chlorinated (no pucks please). I suggest looking around the forums a little more if you are going to go the TFP way. (which is the only way for me).

I have many neighbors with pools that use services, or the pool store and spend a ton of money on chemicals or weekly cleaning. My one neighbor has a pool that has 300 CYA in and can't understand why he keeps getting algae even though he shocks everytime he has people over swimming., but that is another thread I am sure.

As for SWCG or chlorine, yes there are upfront costs to consider and based on what I understand it is basically a push on the cost overall, but it might not be on the work. I spend about an hour of actual time per week on my pool not including the zen like time I get when I brush or vacuum the pool for purposes of relaxation. (see sounds psychotic).

TLDR: SWCG is what I like but ultimately its a personal preference because you can add salt for water feel.
I think pucks have a place. I'm using them now. When I finally got my TF-100, my CYA was only 20 and my TA was close to 200. So I'm using pucks to bring up CYA and reduce TA. When my CYA gets too high, I'll go back to liquid. But by that time, it might be closing time, and I'll see what the CYA is when I open again in late May.
 

Cody

Bronze Supporter
Aug 17, 2014
209
Prosper, TX
FC of 3 for a CYA of 70 on a SWG pool is the bare minimum and should never be used as target. Target is 5 but i use 7-8ppm just for the extra margin of safety.
Yes, I understand that my target should be higher.....so I'll ask in another way...for a NON SWG pool the Target at 70 CYA is 8-10. For a SWG pool at a CYA of 70, the target shows as 5.

Why the difference? I thought chlorine was chlorine. I'm honestly just curious. Since I'm switching to SWG today, I was thinking I'd be working to maintain FC of about 8. The chart says target should be 5.
 

JoyfulNoise

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May 23, 2015
16,226
Tucson, AZ
Salinity changes the ionic strength of the water and, by definition, creates a "strong electrolyte". Ionic strength is the measure of how concentrated the solution is with ionic species. When salts dissolve in water, they do not dissolve as neutral atoms, but as charged ions -

NaClsolid ---> Na+1 + Cl-1

Water, H2O, has a bent structure (looks like Mickey Mouse) and because the oxygen and hydrogen atoms carry a charge, the water molecule has a dipole moment (separation of electrical charge) so there is a slightly positively charged side of the water molecule (where the hydrogen atoms are) and a slightly negatively charged side (where the oxygen atom is). When salt dissolves in water, water molecules experience an electrostatic attraction to the ionically charge atom. Water molecules will surround the ions in different ways to shield the charges so that the solution as a whole is electrically neutral. Because the ionic nature of the water molecules and ionized atoms (sodium and chloride) cause extended, non-random interactions, other electrically charged atoms will also be affected. So the ionic strength plays a direct role in the chemical equilibrium reactions of other molecules. In the case of chlorine, as hypochlorous acid, the pKa (acid dissociation constant) changes from 7.340 at zero TDS to 7.474 at 3000ppm TDS (TDS can be used to vary the ionic strength of the solution). While that might seem significant, chemical reactions are logarithmic in their changes and so the difference in HOCl concentration at 0 TDS and 3000 TDS is 0.001ppm or 1 part per billion.

So the presence of high TDS in the form of salt has little to no implications on the sanitizing power of chlorine.
 
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Rollercoastr

Gold Supporter
May 18, 2016
867
West Bloomfield, MI
I think pucks have a place. I'm using them now. When I finally got my TF-100, my CYA was only 20 and my TA was close to 200. So I'm using pucks to bring up CYA and reduce TA. When my CYA gets too high, I'll go back to liquid.
I agree. Using pucks isn't against TFP methodology unless they're used carelessly. I use them carefully in the off season to maintain pH, FC as well as CYA. It would make no sense to me to dose acid and chlorine and CYA when a puck does all that for me.

When swimming season rolls around, the floater goes onto a shelf and I switch back to liquid chlorine and acid.
 
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madtv126

Gold Supporter
Jul 30, 2018
90
Fort Mill, SC
I think pucks have a place. I'm using them now. When I finally got my TF-100, my CYA was only 20 and my TA was close to 200. So I'm using pucks to bring up CYA and reduce TA. When my CYA gets too high, I'll go back to liquid. But by that time, it might be closing time, and I'll see what the CYA is when I open again in late May.
Tough crowd in here. Yes pucks have a place and the right chemical at the right time is really the key ( in my mind to TFP). If you are testing and using the appropriate resources it doesn't matter what method you use to sanitize the pool. Ultimately, it is about balance and doing what you can to maintain that balance, and luckily hard to get to and maintain that balance if you follow the methods of TFP.

For what is is worth, the forums are amazing and when you do run into a problem the folks here are first rate at solving those issues. KUDOS to everyone who particpates.
 
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jblizzle

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May 19, 2010
43,238
Tucson, AZ
I am going to back-up mguzzy a little bit here.

In the past there were certainly discussions about the "super-chlorination" that occurs within the cell itself, and perhaps even proposed that this was the mechanism that allowed the required FC level relative to the CYA level to be lower. Although, I think this reasoning has fallen away a bit. Whereas the lower FC level is likely more attributed to the consistent nature in which the FC is maintained, unlike the FC swings that can occur when adding bleach daily. The non-SWG chart I think has some wiggle room to account for human nature. Of course, by that logic, a stenner pool might be able to get by with the lower SWG FC levels as well.
 
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mguzzy

Well-known member
Jul 8, 2015
919
OV, CA
I think what makes this a lively debate is that there really is no solid science to backup the technology. At least none that I have ever found published, though there are lots of opinion articles from supposedly knowledgeable people. If I ever get a cool 40K of disposable income I'll buy a cheap mass spec and put it in my garage and do a SWG vs everyone else double blind study. My daughter with the sensitive skin will say, "Daddy why are blind folding me and throwing me in the neighbors pool?"... "It's all in the name of science." I will say in my best BF Skinner voice.
All I know is a SWG works for me and lives up to the claims made by the manufactures... more or less. And it saves me a ton of time working on the pool so I can spend more time posting here.
 

Newdude

Well-known member
Jun 16, 2019
1,939
NY
I only learned this place existsed cuz my cell reached its end of life so in researching i figured i might as well learn what i never needed to before. I had many factors to a TF pool for 6.5 years. Some of it was dumb luck or by accident, but mostly due to the SWG.
 
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Lisabdou

Well-known member
Jul 21, 2019
77
South West TN Memphis Area
And so now that this conversation has hit the stratosphere, what should I do? Traditional Chlorine or Salt?
I travel almost every week so I need /want easy. Plus I can get crazed with testing too much and agonized over tweaking levels of this and that. Easy is what I crave. Also thinking about that floating Bluetooth thing to send me water analytics and tell me what needs to be added.
But will still have a pool service at least initially until I get back in a groove of pool care.
 

Donldson

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Jun 12, 2009
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Despite all the conversation I don't think there was anybody who advised against the SWG...

I will advise against any floating testing thing, those are crazy overpriced for what little they actually do. Actually, that's the same answer for most all pool service companies too :laughblue:
 
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JoyfulNoise

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May 23, 2015
16,226
Tucson, AZ
And so now that this conversation has hit the stratosphere, what should I do? Traditional Chlorine or Salt?
It's not that simple. You have to take into account cost (including what the PB will mark up by) as well as other equipment. SWG's only make sense when you also have a variable speed pool pump and then, why get those without an automation system....so if get the VSP + SWG + Automation, you're now adding a thousand or two extra dollars to your pool build. If that doesn't bother you in the grand scheme of things, then go for an SWG. If cost-cutting is required, then just skip the SWG, add a good length of pipe to the plumbing layout so you can add an SWG in the future.

Also, take into account your pool builders ability here - many will sell you stuff that they themselves have no idea how to install or program. We've seen it here on TFP plenty of times where people will have problems with their SWG, then post up a picture of the equipment install and it's all botched-up because the PB cared more about making a few extra dollars than doing the job right. So if you do decide to go with SWG + VSP + Automation, make sure your PB knows what the heck he's doing or else ask him to contract out the installation to a certified installer for the equipment maker you're going with. Hayward, Pentair and Jandy all have certified installers that you can tap if a PB is unfamiliar with proper installation and setup (but it may cost you extra).
 

JoyfulNoise

TFP Expert
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May 23, 2015
16,226
Tucson, AZ
I opted out of automation because internet is unreliable enough that it’s not worth it. Pump will be VS
Hahahaha....I argue that point all the time with the internet-connected automation fan-boys here. I have a Pentair EasyTouch system with an RF remote - no internet required! I can completely program my automation using the remote or go to the panel and do it there. Yes, it's a 4 line LCD display and you have to do some mental gymnastics to learn how to program the controller, but once you do, it's not that hard. The only time my automation system is ever unavailable is when the power goes out. I get it that everyone loves to have the ability to tour the Great Wall of China and still be able to see if their pool back home is running on the schedule they set OR they like to turn on their spa while they are turning off the freeway but I'm just not that OCD or impatient. I can wait until I get home.
 
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Newdude

Well-known member
Jun 16, 2019
1,939
NY
I have no automation. I have to walk an extra 50 ft to adjust the pump/swg/heater with a few button clicks. They dont need adjusting often, maybe every other week. I think automation is an AWESOME toy. But to me it wasnt worth the cost.
 

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