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Thread: Considering SWG for Inground

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    dandjpool's Avatar
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    Considering SWG for Inground

    Edited for eye breaks. Butterfly

    My auto-chlorinator has seen better days and instead of replacing a bunch of parts I am considering a swg.
    Right now I have a Polaris Watermatic and it is falling apart from 8 years of dichlor running through it.

    Is there anything special I need to know before making a decision?

    The pool is closed all winter. I am in Illinois. Is there a different procedure for opening?
    We usually keep the pool at 82 degrees while open if this matters.

    The pool is abandoned for days at a time while I am out of town so I need it to be self-sustaining (no large fluctuations in pH, TA, TC etc.)

    I know the cell is expensive. How often does it need to be replaced?

    Does it make that much of a difference in water comfort?

    What SWG would you all recommend? The more automatic the better.

    A lot of questions, I know. I searched through the forum for answers and figured it would be best to have someone who has made the change tell me the pros and cons.

    Thank you
    Pool configuration:
    20K Gal inground vinyl liner-1 skim 1 main 2 return
    hayward c3000 cart. filter
    hayward northstar 1.5hp pump
    hayward 250k btu heater
    polaris watermatic G1000 chlorine feeder
    polaris c-300 orp controller
    Polaris 380 with booster
    aquamatic hydraulic pool cover

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    Re: Considering SWG for Inground

    Procedure for opening is the same, you'll just need to make sure your salt level is where it needs to be and add some if necessary.

    One thing to watch out is if you have a coping made of soft stone it needs to be sealed, or there is potential it will get eaten into by salt water with time.

    Cell life is dependent on the brand, but generally 3-7 years when you run it everyday. Sometimes more, really depends on your usage pattern. We had customers whose cells worked for 10+ years. Also not all cells are expensive.

    Main factor in water comfort is salt in the water, it makes your skin less irritated from water and gives that silky feeling.

    I'd recommend Autochlor for obvious reasons, but other people might have their own preferences

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    JasonLion's Avatar
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    Re: Considering SWG for Inground

    I am a big fan of AutoPilot. Their "Digital" model has some nice features the others don't have, like a text display that tells you things like how much salt you need to add to get to the right salt level, and automatic temperature compensation on the percentage setting. The AutoPilot Digital does cost a little more than the other brands, but well worth it for me.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    dandjpool's Avatar
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    Re: Considering SWG for Inground

    I did a little more research. I need to add 500 pounds of salt to my pool to start!?
    I guess it's easier doing that once instead of running out for dichlor every couple of months.
    The Auto Pilot looks very cool and isn't too expensive (digital model).
    Can I install that before my heater? Will it mess up my heater? It's the only place I have room. My returns go right into the ground from the heater.
    If I don't get the Auto Pilot I am looking at the Aqua-Rite. The main reason for not choosing the Aqua Pilot is the 220 requirement.

    Thanks for your help.
    Pool configuration:
    20K Gal inground vinyl liner-1 skim 1 main 2 return
    hayward c3000 cart. filter
    hayward northstar 1.5hp pump
    hayward 250k btu heater
    polaris watermatic G1000 chlorine feeder
    polaris c-300 orp controller
    Polaris 380 with booster
    aquamatic hydraulic pool cover

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    Re: Considering SWG for Inground

    I wouldn't recommend doing that unless your heater has a titanium core as it will reduce lifespan of a heater.
    500 pounds sounds about right if you have 0 salt to start with. However you should check before adding salt, as you may already have some salt in the water.

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    dandjpool's Avatar
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    Re: Considering SWG for Inground

    That is what I figured. I think I can make it work after the heater but it will involve some extra pvc which I was trying to avoid.
    The chlorinator I have now is installed before the heater and booster pump.
    The heater core has corroded twice in 10 years and I have had to replace the O ring in the booster pump every other year.

    Since the SWG still makes chlorine from salt and is still caustic enough to cause issues with my heater, how is it less harsh on people's skin or eyes?
    Pool configuration:
    20K Gal inground vinyl liner-1 skim 1 main 2 return
    hayward c3000 cart. filter
    hayward northstar 1.5hp pump
    hayward 250k btu heater
    polaris watermatic G1000 chlorine feeder
    polaris c-300 orp controller
    Polaris 380 with booster
    aquamatic hydraulic pool cover

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    JasonLion's Avatar
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    Re: Considering SWG for Inground

    The water coming out of the cell can have a fairly high chlorine level. Mixed into the pool the chlorine level is significantly lower. That higher chlorine level, which exists only in the pipes, can cause metal corrosion in some cases. This effect can be amplified if the cell is active when the pump shuts off. Then the higher chlorine level water can sit in the heater for hours without getting diluted into the bulk of the pool water.

    The softer on your skin effect is mostly because there is salt in the water. The bodies natural salt level is higher then the pool water salt level. By adding salt you bring the pool water closer to the bodies salt level and reduce the irritation. You can get the same effect by adding salt without having a SWG at all. There is also a much smaller effect from the slightly lower chlorine levels you can have in the pool when using a SWG as compared to most other chlorine sources.

    Also, how something feels on your skin has only a lose relationship to how it affects metal parts. Metal corrosion and skin feel are based on different effects. A few things, like acid, have similar effects on skin and metals. But many other factors, like salt, affect the two quite differently.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    dandjpool's Avatar
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    Re: Considering SWG for Inground

    OK, I totally understand.
    I read a little about it and the salt itself aids in getting rid of some of the things that pollute water so the chlorine needed is lower.
    Plus, since humans are already salty the water is friendlier to our chemical makeup
    Am I understanding that correctly?

    I'm about 95% sure I am going to take the leap. After pricing out some of the replacement parts for my Polaris Watermatic chlorinator it makes more and more sense.
    The pluses are:
    No more dichlor which means no more insanely high CYA.
    No more replacing parts on my current chlorinator.
    I will have a little more room on the pad to work with.
    No lugging 50 pound pails of granulated chlorine.

    Minuses:
    500 pounds of salt!
    Less tolerant to fluctuations in pH etc.
    Will create more drag in my maze of pvc.
    Pool configuration:
    20K Gal inground vinyl liner-1 skim 1 main 2 return
    hayward c3000 cart. filter
    hayward northstar 1.5hp pump
    hayward 250k btu heater
    polaris watermatic G1000 chlorine feeder
    polaris c-300 orp controller
    Polaris 380 with booster
    aquamatic hydraulic pool cover

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    JasonLion's Avatar
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    Re: Considering SWG for Inground

    Quote Originally Posted by dandjpool
    Plus, since humans are already salty the water is friendlier to our chemical makeup
    Am I understanding that correctly?
    Yes.

    Quote Originally Posted by dandjpool
    Less tolerant to fluctuations in pH etc.
    There isn't any difference in tolerance of PH changes. Using a SWG tends to cause the PH to rise, just as using trichlor tends to cause the PH to fall (but for different reasons). In both cases you can balance the water to minimize the effect, but either way you always need to keep an eye on the PH and make sure it doesn't go out of range.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Considering SWG for Inground

    Quote Originally Posted by dandjpool
    I read a little about it and the salt itself aids in getting rid of some of the things that pollute water so the chlorine needed is lower.
    not quite
    it's more to do with the water passing through the cell and getting constant shock, which removes chloramines and helps to kill bacterias faster

    salt itself is an antiseptic, but it wouldn't kill bacterias which are common in swimming pools

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    Re: Considering SWG for Inground

    Quote Originally Posted by Strannik
    Quote Originally Posted by dandjpool
    I read a little about it and the salt itself aids in getting rid of some of the things that pollute water so the chlorine needed is lower.
    not quite
    it's more to do with the water passing through the cell and getting constant shock, which removes chloramines and helps to kill bacterias faster

    salt itself is an antiseptic, but it wouldn't kill bacterias which are common in swimming pools
    I see. I am guessing 3500 ppm isn't high enough to have an effect.

    Does the cell give a constant shock at varying levels or is it on/off as needed?
    It must be one or the other or you couldn't regulate or super-chlorinate.
    Pool configuration:
    20K Gal inground vinyl liner-1 skim 1 main 2 return
    hayward c3000 cart. filter
    hayward northstar 1.5hp pump
    hayward 250k btu heater
    polaris watermatic G1000 chlorine feeder
    polaris c-300 orp controller
    Polaris 380 with booster
    aquamatic hydraulic pool cover

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    dandjpool's Avatar
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    Re: Considering SWG for Inground

    Quote Originally Posted by JasonLion
    There isn't any difference in tolerance of PH changes. Using a SWG tends to cause the PH to rise, just as using trichlor tends to cause the PH to fall (but for different reasons). In both cases you can balance the water to minimize the effect, but either way you always need to keep an eye on the PH and make sure it doesn't go out of range.
    This is very good to know! I must have misread somewhere that the pH needed to be kept from 7.2-7-6 or you will come home to a cloudy pool.
    It was one of my biggest reasons for not taking the leap.
    We go out of town quite a bit and I hate when I get back and my pool is green.

    I think you helped me get my CYA in control last year (along with frustrated pool mom) which eliminated the bouncing around of my FC levels and all that goes along with super high CYA.

    Thanks again.
    Pool configuration:
    20K Gal inground vinyl liner-1 skim 1 main 2 return
    hayward c3000 cart. filter
    hayward northstar 1.5hp pump
    hayward 250k btu heater
    polaris watermatic G1000 chlorine feeder
    polaris c-300 orp controller
    Polaris 380 with booster
    aquamatic hydraulic pool cover

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    Re: Considering SWG for Inground

    Quote Originally Posted by dandjpool
    Quote Originally Posted by Strannik
    Quote Originally Posted by dandjpool
    I read a little about it and the salt itself aids in getting rid of some of the things that pollute water so the chlorine needed is lower.
    not quite
    it's more to do with the water passing through the cell and getting constant shock, which removes chloramines and helps to kill bacterias faster

    salt itself is an antiseptic, but it wouldn't kill bacterias which are common in swimming pools
    I see. I am guessing 3500 ppm isn't high enough to have an effect.

    Does the cell give a constant shock at varying levels or is it on/off as needed?
    It must be one or the other or you couldn't regulate or super-chlorinate.
    Even 35% will not be enough, salt is VERY mild antiseptic.
    Shock would be different as electrical charge between the plates is different and level of produced chlorine is different. It only shocks the volume of water that passes through the cell.

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    Re: Considering SWG for Inground

    Quote Originally Posted by JasonLion
    I am a big fan of AutoPilot. Their "Digital" model has some nice features the others don't have, like a text display that tells you things like how much salt you need to add to get to the right salt level, and automatic temperature compensation on the percentage setting. The AutoPilot Digital does cost a little more than the other brands, but well worth it for me.
    So after tons of research I've decided to go with the AutoPilot. Surprisingly my wife is all for spending the extra money even if I have to get an electrician to run the 220 line!?
    The main reason for this choice is the bypass manifold and the automation. Since my pump is a little over powered for my setup I figured having a pressure bypass would keep me from buying a new cell every year. (Plus it looks cool as **** ) And having the pump controlled by the chlorinator is an added bonus. I don't like the analog timer I have.

    I was going back and forth between the Cubby Digital and the Digital until I saw that you can convert the Autopilot Digital to 115vac.
    Is there any reason I wouldn't want to do this beside the extra amp draw? I think that 3amps will still be low enough to avoid tripping the GFCI breaker
    Pool configuration:
    20K Gal inground vinyl liner-1 skim 1 main 2 return
    hayward c3000 cart. filter
    hayward northstar 1.5hp pump
    hayward 250k btu heater
    polaris watermatic G1000 chlorine feeder
    polaris c-300 orp controller
    Polaris 380 with booster
    aquamatic hydraulic pool cover

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    JasonLion's Avatar
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    Re: Considering SWG for Inground

    It only makes a very small difference what voltage the SWG is set up for. It makes more of a difference what voltage the pump is setup for, but it still isn't that big a deal for a smaller pump. You lose a couple of percent efficiency to electrical loses in the wiring. Those loses are larger at lower voltages. For low power equipment, like a SWG, the total amount lost is trivial. For higher power devices, like large pumps, the loses become more significant.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  16. Back To Top    #16
    dandjpool's Avatar
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    Re: Considering SWG for Inground

    OK, one more question then I am going to purchase.

    I have a 20K gallon pool. Will the SC-36 says it is good for up to 20K pools.
    Should I get a bigger cell or will the 36 suffice?
    Pool configuration:
    20K Gal inground vinyl liner-1 skim 1 main 2 return
    hayward c3000 cart. filter
    hayward northstar 1.5hp pump
    hayward 250k btu heater
    polaris watermatic G1000 chlorine feeder
    polaris c-300 orp controller
    Polaris 380 with booster
    aquamatic hydraulic pool cover

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    Re: Considering SWG for Inground

    i would
    american SWGs usually are rated based on 24/7 operation so best to have some backup up your sleeve

  18. Back To Top    #18
    JasonLion's Avatar
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    Re: Considering SWG for Inground

    AutoPilot is fairly conservative in their cell size recommendations, so an SC-36 should be fine if your sumer time pump run time is 8 hours or over. Personally, I like to get a cell one size larger than they recommend so the cell doesn't need to be replaced as often, but the standard size should work just fine. Getting a cell two sizes larger than recommended can cause minor annoyances, the percentages get so low that you lose precision in the percentage adjustment, so don't over do it.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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