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Thread: Salt reading changing with temp of water.

  1. Back To Top    #1

    Join Date
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    Salt reading changing with temp of water.

    I have a new SWG, installed last year. I noticed that the higher the temperature of the water goes, the lower the reading of the salt level goes. I called the Manufacturer and they said this is normal. I had another one for over 9 yrs before replacing this one and I don't remember it doing this. The fluctuation isn't great, just a hundred up or down but I wanted to ask here and see if this is something I should worry about and call them back and demand action. Water is great. One thing I notice is I have to run this unit higher, like at 50 % all the time whereas when I got my other one when it was new I had to keep it at 20 % or shut it off a lot because the chlorine would get too high. I wonder if they now make them to put out weaker and therefore you have to run them longer and they wear out faster, more money for them when it gives out and you have to replace it. Thanks for the help.
    18X36 Vinyl IGP, SWG,1HP Hayward Superpump, Sand Filter

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    Re: Salt reading changing with temp of water.

    None of the SWG's measure the actual salinity level and they use different methods to determine the salinity. Also, some SWG's have temperature compensation while others do not.

    Usually it is the opposite, the warmer the water gets the higher the salinity reading. Most units have a large operating range for the salinity and it is usually no problem for the temperature differences.

    You don't mention if you switched brands of SWG's or cell sizes which both could give different outputs.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
    Hayward Aqua Rite T-15 SWCG, Jandy LXi 400k BTU NG heater, 350 sq.ft. of Sun Star solar panels, TF-100 Test Kit, Dolphin s300i Cleaner
    Test Kits . Pool Math . Chlorine/CYA Chart . The SLAM Process

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    mikemass's Avatar
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    Re: Salt reading changing with temp of water.

    Quote Originally Posted by ping View Post
    the warmer the water gets the higher the salinity reading.
    This has been my experience as well. But we are talking 100, 200 ppm difference tops.
    25 + year pool owner. Current pool (going on 11th year) - 38K gallon in ground Gunite/White Plaster, Spillover Spa, Hayward Cartridge Filter, Hayward 450k BTU NG Heater, Hayward Goldline Aqua Logic control with T-Cell-15 Salt Water Cell, Dolphin Explorer.
    You Need: Bleach, a A Test Kit & a Bookmark to "Pool School". Now what's your question?

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    Re: Salt reading changing with temp of water.

    No, cell size the same. I went from Goldline and when I ordered online they sent me SwimPure Plus. I think Hayward made both but not sure. Both were the 40,000 gallon cell size, and yes, the higher the temperature of the water the lower the salinity reading goes. I know this is the average of all the readings and it is not off by much, just 100 or 200 but I like to keep it at 3200 if I can. The older model never did this so don't know why this newer model does it and as I said before, I don't feel it is as powerful. I used to only keep it at 20 % but now I have to keep it at 50% to maintain the chlorine level. My chemicals are all perfect, thanks to this wonderful site so it isn't water chemistry doing anything. Just hate to think there might be something defective and the company is just giving me lip service.
    18X36 Vinyl IGP, SWG,1HP Hayward Superpump, Sand Filter

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    Re: Salt reading changing with temp of water.

    Run an OCLT to rule out organics consuming the FC.

    How many gallons is your pool? With gallons, SWG %, and run time we can calculate how many ppm of FC your system should be producing each day.

    My 16,500 gallon pool is using around 2ppm of FC each day right now and my settings are 11 hours with the SWG at 50%.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
    Hayward Aqua Rite T-15 SWCG, Jandy LXi 400k BTU NG heater, 350 sq.ft. of Sun Star solar panels, TF-100 Test Kit, Dolphin s300i Cleaner
    Test Kits . Pool Math . Chlorine/CYA Chart . The SLAM Process

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    Re: Salt reading changing with temp of water.

    My water chemistry is fine, water crystal clear and no CC. My pool is 25,000 and I run it around 12 hrs a day. Takes 9 1/2 hrs to turn water over once. I don't know what an OCLT is. Ok went back and looked, I see what the test is. I'll run that and see if I am losing any chlorine but I don't really think so.
    18X36 Vinyl IGP, SWG,1HP Hayward Superpump, Sand Filter

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    Re: Salt reading changing with temp of water.

    A 12 hour run time with 50% setting will only make 1.7ppm of chlorine in a day for your pool size. That seems to me that everything is fine with the pool and SWG.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
    Hayward Aqua Rite T-15 SWCG, Jandy LXi 400k BTU NG heater, 350 sq.ft. of Sun Star solar panels, TF-100 Test Kit, Dolphin s300i Cleaner
    Test Kits . Pool Math . Chlorine/CYA Chart . The SLAM Process

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    Re: Salt reading changing with temp of water.

    Since it got a little colder the water temp went down and my chlorine reading is up from 8.5 to 10.5 so its working great. I might turn it down a tad. I also upped my TA, it was at 50, now at 80 and I also added stabilizer which was at 50 so I wanted it a little higher. Guess I won't worry about the salinity reading as long as it doesn't go nuts. Thanks for all your help.
    18X36 Vinyl IGP, SWG,1HP Hayward Superpump, Sand Filter

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