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Thread: Inconsistent salt results...help!

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    Inconsistent salt results...help!

    I haven't added salt to my pool in a couple of years. My Jandy unit has always shown between 3.0-3.5, and occasionally I take the water to a local Leslie's for a second opinion, and he's always said it's fine.

    About a month ago, I started getting error codes on the Jandy that indicated I needed to clean the flow sensor (which, if I understand correctly, is the part that reports back to the hardware about the salt concentration). I cleaned it with a lightly abrasive sponge, just as instructed. I didn't see ANY visible change as I cleaned it. (There was no coating, debris, or anything else -- the contacts looked bright and shiny before, and are bright and shiny afterwards.)

    When I reassembled it and turned it back on, the Jandy now showed 1.7, which is dangerously low. I double-checked this with some salt cell test strips (Aquapure) which confirmed about 1.5. So I bought a few bags of salt, dumped them in, followed instructions (turned salt cell off for 24 hours, mixed the water well, etc.). The Jandy barely budged -- about 1.8. According to my calculations I have about a 15k gal pool. But who knows. Maybe I mis-measured it and it's 20k. (Hard to tell because it's odd-shaped.)

    Long story short...after 5-6 strips to the store over 2 weeks to get 2-3 bags of salt each time, I finally got the Jandy to report 3.0. I double-checked this with Aquapure check strips which showed me about 2.9. I figured OK, at least we're back in "acceptable" territory, so I turned the salt cell back on, and the Jandy appears to be working and isn't reporting any errors.

    However, two days later, I checked the Jandy, which now shows 4.1 salt concentration -- YIKES. I used the test strips which still show 3.0. I turn it off and on again; it shows 3.0. Then it climbs to 4.0.

    Basically...I'm wondering if this (older) Jandy unit could be malfunctioning (even though there are no error codes). Do I trust the Jandy? Or do I trust the test strips? Or what?? It seems like every time I test I'm getting different answers, and now I don't know what to do.

    The water tastes noticeably salty, if that means anything.
    Los Angeles (San Fernando Valley)
    15k gallon in-ground (IG) pool (I believe it's plaster)
    DE filter (Heyward), using cellulose instead of DE
    Jandy APURE1400 3-port salt cell

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    Re: Inconsistent salt results...help!

    It could be a combination of both being off. As long as the SWG works you shouldn't do anything to correct it. My SWG reads 500 points higher than any test that I have performed, I have the Taylor K-1766 salt test kit, and I just ignore the results as the SWG works fine.

    It might take a couple of days for the SWG to settle down. Have you brushed the pool really well since you added the salt, that might help to mix up the water some.

    If the SWG stops working, we can troubleshoot it then.
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    Inconsistent salt results...help!

    Just a technical point here - SWG cells essentially measure TDS and that is a reflection of the electrical conductivity of the water passing through the cell. TDS is the measure of all conducting ions in solution. There is no way for the cell to measure the salt concentration directly. This is why, so often, SWG cells show a salt value that differs from test strips or reagents. Also, there is a temperature effect as well. For example, most Pentair IC cells will have a +300ppm/5 deg F temperature drift. Some SWG cell manufacturers account for this electronically, others do not.

    The moral of the story is this - add salt to your pool to a concentration that makes your SWG happy and only use strips or reagents to check you're near the correct value.

    As as for your particular case, given the age of the cell, you could be nearing the end if it's useful life as flow sensors and conductivity sensors start to act flaky. If you feel confident looking at the control electronics, you might remove a cover in the cell controller (with all electrical power shut OFF please!) to see if there are any components on the board that look burned out. Often times the cells are pretty durable but the control electronics are the weak point.

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    Re: Inconsistent salt results...help!

    I took some water to Leslie's today (they just got a new salt concentration measuring device) and he measured it at 5.5 (off the charts, basically).

    Oops.

    Well, so now I have extremely high salt, which puts me at risk for scaling. Due to the water shortage in southern California, I can't think about emptying the pool. What's my next best option? The guy at the pool store said I'd be wise to use some calcium descaler regularly. What's the TFP wisdom on this?

    Hopefully my salt cell is working correctly (I will know in a couple of days) so at least it's going to use all that excess salt to make me chlorine!

    Forgot to say: as always: THANK YOU to you guys for helping me through this. It's really appreciated.
    Los Angeles (San Fernando Valley)
    15k gallon in-ground (IG) pool (I believe it's plaster)
    DE filter (Heyward), using cellulose instead of DE
    Jandy APURE1400 3-port salt cell

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    Inconsistent salt results...help!

    Not sure about your model, but my IC40 shuts down if the salt concentration is too high (you can burn out the cell plates if the conductivity of the solution is too high).

    I was worried you had bad salt readings and went over board. As I said, I had gotten bad numbers from the pool store (before I knew better) and my salt got too high.

    Without water draining, there's not much you can do but drain and wait for rain. Your water restrictions are pretty intense.

    Your other option is to find a company that does reverse osmosis water treatment. It's about 2X the cost of drain & fill but with your water restrictions it's your only option. RO treatment can desalinate your water but it will also remove everything else as well (calcium, sodium, CYA, etc). Typically you have to reduce your FC level to 0 before they will filter because chlorine destroys the RO membrane. There is a waste water fraction (typically 20% of the water is rejected as waste in good, high pressure cascaded RO systems) so you will have to refill some with either municipal water or water trucked in.

    Something like this -

    poolservicestech.com/tag/reverse-osmosis/


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    svenpup's Avatar
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    Re: Inconsistent salt results...help!

    Several issues here:

    Salt does not cause scaling; calcium does. If the pool store told you that you should ditch them.

    Are you reporting salt in parts per thousand? We usually talk in ppm.

    A cell at the end of its life will start reporting low salt, as will a cell with scaling. You haven't reported any other levels so we can't really guess. Have you examined the cell? What is your CH? How frequently do you adjust pH and do you frequently let it get too high?

    The flow sensor measures (not surprisingly) flow. The system can't work if there isn't enough flow over the plates. This is different than the salt sensor which measures (indirectly) salt. I am not sure which sensor you sanded or if that was the right course of action but it seems like you are maybe acting without fully understanding the issues.
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    Re: Inconsistent salt results...help!

    The Jandy sensor is a tri-sensor, it measures flow, salinity, and temp in the same sensor.

    I would try to run the SWG and see if it runs or not.

    I'm not sure why they mention scaling due to excessive salt, you get scaling from excessive calcium and a high pH for the most part.
    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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    Inconsistent salt results...help!

    The problem with running this electrochemical cell at higher than recommended salt levels is that the conductivity of the solution can get too low which will result in a voltage drop decrease across the plates and a current increase (up to the current limiting rating of the electrical circuit driving the cell). Going outside an electrochemical cell's operating point can lead to all sorts of problems (greater ohmic heating, side reactions or decreased cell efficiency, etc). High current can lead to changes in the current density distribution across the anode plate which can lead to non-uniform erosion. I used to see this all the time when I worked with electrochemical plating cells in industry.

    If your salt level is truly very high, then it's advisable to correct that. The alternative is running the cell in a high salt condition until it burns itself out. Typically the plates in an SWG are either copper or steel coated with a mixture of precious metals (platinum, ruthenium, titanium, etc). Once you burn through the coating, you can expose the underlying metal plate. Not typically a good idea.

    It might be a good idea to get your own salt test kit from Taylor so that you can best determine your salt level on your own.


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    JayBauman's Avatar
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    Re: Inconsistent salt results...help!

    This happened to me last year. I noticed that sometimes the "no flow" light would be on, my salt reading would be different, and the cell reversal light would stay on during these "excursions". It occurred randomly for a few months, then quite frequently for a few weeks. Eventually it stayed in this mode constantly.

    Jandy sent me a new sensor under warranty, and (once I figured out the correct setup) it fixed my problem.
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