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Thread: Why doesn't salt just keep going up? Or does it...

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    Why doesn't salt just keep going up? Or does it...

    Quick question - Just about everything added to the pool contains some salt in it (incl bleach, soda ash, baking soda). I understand that it might not be much salt, but it is some salt.

    Why doesn't the salt level just continue to rise - slowly but continuously? Why don't you eventually end up with a pool that has too much salt?

    I understand that with a sand filter there is some water loss with backwashing which may explain why the level doesn't go up, but what about with a cartridge filter?

    Is the process so slow that the pool needs to be drained for some other reason (such as liner replacement), well before it becomes a problem?
    In-ground (24x40) vinyl pool (~25k gallons), Pentair Clean and Clear Plus cartridge filter (Model CC420P - 150 gpm), Pentair 1.5 HP pump, Pentair MasterTemp 250 Heater. TF100 test Kit.

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    Re: Why doesn't salt just keep going up? Or does it...

    It certainly does in my pool. The salt level rises by about 1200 ppm a year.

    I have minimal splashout and don't backwash. I end up draining about half of the pool during the winter due to high calcium and salt levels.

    I think you don't hear about this a little more often because people who don't have salt pools think that there is no salt in the water and don't test for it. This is far from reality though, as you mentioned nearly everything adds some form of salt to the water. By far, acid is the biggest offender as it's chloride content is the near equivalent of adding 5 pounds of salt per gallon of acid. This equates to 18ppm in my pool and substantially more in typical sized pools.
    -Brian-
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    JoyfulNoise's Avatar
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    Re: Why doesn't salt just keep going up? Or does it...

    In your part of the country, it would be rare to see salt rise much in season. With such a short swim season and the removal of water during winterization, not to mention snow melt and rain overflow, I doubt you would have a problem with salt build up.

    In arid climates such as mine, salt can build up more quickly but it is generally not a problem. Calcium is the bigger issue and that typically requires a partial drain to correct or reverse-osmosis (RO) to fix.


    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Mod Squad pooldv's Avatar
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    Re: Why doesn't salt just keep going up? Or does it...

    Good theory. Just to add the in between climate. We were in drought for several years and my salt level was above 5000 ppm. My SWG reports high salt above 4100 ppm but continues to make chlorine so it wasn't a big deal. The last 2 years we have been extremely rainy and I have had to add salt and CYA several times each year.
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    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

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    Re: Why doesn't salt just keep going up? Or does it...

    Note bdavis' location. Those of us in areas of 30+ inches of rainfall add a LOT of pristine water that he does not get.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: Why doesn't salt just keep going up? Or does it...

    Ok, I think I understand. Forgot about lowering the water level for a winter closing.

    As far as adding water due to rain / snowmelt - that would only affect the salinity if the rain caused the pool to actually overflow, right?

    If my pool had an overflow pipe / drain - where would it be located and how would I recognize it?
    In-ground (24x40) vinyl pool (~25k gallons), Pentair Clean and Clear Plus cartridge filter (Model CC420P - 150 gpm), Pentair 1.5 HP pump, Pentair MasterTemp 250 Heater. TF100 test Kit.

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    Mod Squad pooldv's Avatar
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    Re: Why doesn't salt just keep going up? Or does it...

    Yes, it only impacts if the pool overflows. There are usually two types of overflow. One is a grate at the waterline that leads to a PVC that leads to PVC pipe. The other is a pipe plumbed at the waterline inside a skimmer or an autofill. Both pipes will lead to a point downhill from the pool or to a drain line.

    If your pool has never filled to overflowing after a BIG rain then you probably have an overflow line somewhere.
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    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

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