Salt vs Chlorine

[chiefwej]

First, I'll say I have a SWG and I love my salt pool. I would never have it any other way. But my pool was built as a salt pool, no stone work anywhere. My pool builder said: "Salt or stone, pick one but you can't have both". We picked salt. The pool was built with no coping. It has a textured vinyl finished concrete deck that has a cantilevered edge.

The real downside of a salt pool is that it erodes natural stone near the pool. You can seal the stone to try to slow it down, or use harder, less porous stone, but eventually it will damage any stone work. So if planning a salt pool, design it with that in mind.

 

[trbvm]

Maybe not at the lowest speed. It is a little bit of trial and error to determine what the lowest speed that has enough flow rate for the salt water chlorinator to work.

I still have to get this installed, read the manual, experiment, etc..etc. Not sure how to determine if the chlorinator is 'working' at a particular speed. Is there a 'light' or something that says it is working (Hayward model)?

 

[pooldv]

Can the SWG effectively produce chlorine when a variable speed pump is running at its lowest speed?
That way, the pump can run for longer without incurring much cost (low speed) plus get the chlorine in the pool..

Yep, ours makes chlorine at 900 rpm, but when the filter gets dirty I get flow errors. Settled in on 1100rpm to get good skimming action and make chlorine with no flow errors. Pump draws 150 watts at 1100 rpm. Cheap!

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There should be a light that indicates it is working, usually green, or not working, usually red.

 

[trbvm]

Yep, ours makes chlorine at 900 rpm, but when the filter gets dirty I get flow errors. Settled in on 1100rpm to get good skimming action and make chlorine with no flow errors. Pump draws 150 watts at 1100 rpm. Cheap!

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There should be a light that indicates it is working, usually green, or not working, usually red.

Ah.. ok. Thanks for the clarification. These are exciting times, indeed. Cant wait to get it all done!

 

[chem geek]

While my new pool isn't quite finished (initial fill happening RIGHT NOW), I can offer my motivation for going with the SWCG. Salt water generators help break down the cloramides that are the main contributors to the "chlorine smell" and red eyes typically associated with having a pool. I am hoping that I will be able to keep these CCs down to basically undetectable levels without too much intervention.

There is a lot misleading in these statements that sound like they are being repeated by what SWCG salesmen say. First of all, its chloramines, not chloramides, and the outdoor residential pools on this forum have minimal combined chlorine (CC) including chloramines regardless of how they are dosed -- be it manually from chlorinating liquid or bleach or automatically from a Stenner pump or The Liquidator, or whether from a saltwater chlorine generator. In my own pool that I manually dose with 12.5% chlorinating liquid, I consistently measure <= 0.2 ppm CC which is the limit of the Taylor K-2006 FAS-DPD test using a 25 ml water sample and that's with a pool cover on for about 23 hours each day.

The "typically associated with having a pool" must be referring to commercial/public pools or to residential pools NOT using the TFP methods. This has very little to do with an SWCG system.

 

[ummgood]

Just for clarity my pool isn't finished but I have read up and decided to do the TFP method prior to even signing my contract. Initially all my pool quotes had a lot of Oklahoma flagstone as coping and steps around the pool and I knew that wasn't ideal with salt. Then one builder quoted me all with flagstone looking Belgard pavers and then that gave me the idea to do salt. The reason I decided to do salt was for convenience. There are several times of the year that I am out of town either for work or vacation. usually about 4 to 6 weeks of the year. While I know this isn't ideal I do know that once I learn how to dial in the salt chorinator it is less work for either my wife or someone watching the house to do in order to maintain the pool. I couldn't imagine asking someone to lug bleach. So it was either SWG or put in a Stenner pump for ease.

 

[duraleigh]

As chem geek says, do not listen to any hype about SWG's and their ability to keep a more pristine pool. Buy an SWG because you want the convenience (they are terrific) and you don't mind paying the front money for that convenience.

 

[ComputerGuyInNOLA]

As far as a SWCG will damage any stone, I don't believe it. I am sure it can damage softer stone if it accumulates through splash out and you don't get a lot of rain (or hose down your deck). Our travertine looks like the day it was installed. Of course it was sealed. I would not give up my SWCG for anything due to the convenience. My wife would probably kill me if she had to haul bleach from the store every week or so.

 

[chem geek]

As far as a SWCG will damage any stone, I don't believe it. I am sure it can damage softer stone if it accumulates through splash out and you don't get a lot of rain (or hose down your deck). Our travertine looks like the day it was installed. Of course it was sealed. I would not give up my SWCG for anything due to the convenience. My wife would probably kill me if she had to haul bleach from the store every week or so.

Well, believe it, and you nailed the reason. It's the accumulation of salt from splash-out and evaporation cycles. So it's worst in areas without summer rains and with hot dry (low humidity) air. This paper describes the salt recrystallization pressure that is the source of the problem. This link shows photos of damage mostly to unsealed concrete. This link shows photos of damage mostly to unsealed soft stone. This link explains how one can use sealers to prevent such damage.

Though non-SWCG pools would also experience this problem, it's somewhat non-linear where a certain salt threshold level will accelerate the problem because at a certain concentration of salt with a certain rate of splash-out and certain rate of evaporation and lack of rain dilution the buildup and evaporation is fast enough to have significant pressure to crack the concrete or stone and have pieces flake off. Below that critical set of rates, there is still some pressure and some damage, but a lot less so it takes a lot longer to see.

 

[ComputerGuyInNOLA]

Chemgeek, thanks for that post. I live in a place that rains nearly every day in the summer and we have super high humidity. When a I first moved to New Orleans 30 years ago I thought I would have to move back to N.C. because it felt like I was breathing water!

 

[Paris69]

Never owned a pool before but I have been in both many times with no issues. I have asked several pool builders their take on salt vs. man made during my quote process and they all said similar words. If they were to build a pool, it would be man made. Each of them had their own reasons which we have all heard before here on TFP. Either way build it to your liking an have fun. They both again have pros and cons. Neither one is better than the other. Good luck.