How do SWG's work?

frustratedpoolmom

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#1
Not sure if this is for "The Deep End" or "Just Getting Started"...

We all need to visit pool school now and then. I know very little about SWG’s so I have some questions after reading the article about Water Balance for SWG’s in pool school.

Will CC’s not form in a SWG pool? What about pools that require winterization, would you still shock a SWG then? The phrase "never need to routinely shock" this applies to any properly balanced pool, yes?

If you are going to leave the SWG pool unattended for a week or so, is it more advisable to leave the equipment running, or shock and turn off equipment (assuming no one can check on things for you).

Once your salt is in and SWG is running, do you still have to add CL? Or does the SWG put it in? I guess I really don’t understand how they work....

Why does SWG demand a higher CYA level?

Thanks all you pool guru's for helping us all understand things better. :hammer:
 

JohnT

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Apr 4, 2007
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#2
The SWCG runs an electrical current through the water. The current breaks down the salt, NaCl, and among other things, Chlorine is produced. You don't need to add chlorine routinely.

The chemistry of the pool is very close to that of any other pool. CCs can form, but the normally constant chlorine levels and the chlorination process itself seems to make them very unlikely. They are fairly maintenance free. Just turn it on and leave it on. Adjust the chlorination rate to accommodate your pump run time and your pool's particular requirements and leave it alone.
 
G

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#3
This thread goes into more depth than the pool school ariticle, which Sean wanted to be very simple. It used to be a 'sticky' but Sean has decided to unstick most of them because of pool school. I think it will answer several of your questions
viewtopic.php?f=21&t=3663

to answer some of of your other questions:

The water going through the cell is being 'superchlorinated' to very high levels whenever the cell is generating so this is why shocking is rarely necessary. Manually chlorinated pools, even properly maintained ones, do not have this superchlorination occurring so shocking is more likely to be needed.\

If you are gong away leave the equipment running. You would normally leave the pump on, right? If you don't the pool with probably turn green whether you have a SWG, a trichlor feeder, or other automatic means of dispensing chlorine. If you do this you do not need to shock before hand.

If you shut the pool down for the winter use normal winterizing procedures. If you run the pool realize that algae doesn't really grow in cold water, nor does a SWG generate chlorine, so it's really not a problem. Usually in winter if the pool is not closed you would cut back on pump run time (same as any other pool) and turn the generator output down a bit.
 

tnthudson

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Mar 31, 2008
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#4
To follow up on waterbear's post, I've had a SWG since April, and I've only had to shock with additional CL once (so far). You can jack the SWG up to 100%, which 'shocks' the pool for 24 hours, but I followed the advice on the SWG forum on this site and used CL manually for the shocking.
The SWG forum has some great posts explaining SWG's, and giving advice on where to keep your chemistry. For me, I keep it close to where the manufacturer recommended, but tweak it just a little (namely the CYA level and TA) to get it closer to where JasonLion and waterbear recommend in the SWG forum.
I have noticed, now that my CYA level is finally coming up, that I was able to decrease the output on the SWG (more CYA means more CL stays active longer in the pool, so I don't need to output as much CL with the SWG now that my CYA level is up).
On my SWG, you can set it at 0% - 100% in increments of 20%, which seems to work fine; if the CL level is a little high when I test on the weekend, I'll lower it a notch for the next week and retest it. This output percentage translates into how much time the SWG is 'charging' the salt water and outputting CL by doing so.
I did go on vacation for 10 days in June, left the pump and SWG on its regular timer schedule, and came back to a beautiful pool - wow! That alone made me feel good about a SWG.
You do taste some salt (the level of 3700 or so ppm is WAY less than the ocean), and we like the soft, silky feel of the water. You also have to watch pH, as it tends to rise due to the 'outgassing' that happens as it is producing CL; a little muriatic acid takes care of that, however.
Hope this helps some.
 

frustratedpoolmom

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#5
Great replies, thanks I understand alot better now. I swam in a friend's family member's SWG pool last summer and it didn't taste salty that I could tell, the water did "feel" better.

If and/or when I ever upgrade to a different pool I would definetly like an SWG. Sounds like a great addition, all the benefits of auto chlorinator but none of the downsides....