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Thread: Differences in Salt Level Readings

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    Question Differences in Salt Level Readings

    I have been monitoring the salt level in my spa on a daily basis as part of my data gathering to address another issue. I have been comparing the readout from the IntelliChlor SWG to the drop test results from the Taylor kit. As indicated below, there have been some significant deviations between the 2 results on certain days (e.g. on July 18). I have been diligent to take the readings during the same time of day, with the circulation pump on & obtaining the water sample (for the drop test) at a depth of about 18". Could someone offer some thoughts on the deviations? Thank you so much.

    SALT LEVEL READINGS

    DATE/ SWG READOUT/ TAYLOR KIT

    July 5 3350 3200
    July 6 3350 3000
    July 7 3350 3000
    July 8 3200 3300
    July 9 3950 3200
    July 10 3000 2800
    July 11 3000 3000
    July 12 3200 3200
    July 13 3150 3000
    July 14 3800 3200
    July 17 3500 3000
    July 18 3450 2400
    Kit
    14' X 11' rectangular in-ground spa; 2,360 gals; plaster/gunite; SWCG (Pentair IntelliChlor); Pentair Intelliflo varaible-speed pump; EasyTouch4 control system; cartridge filters; auto cover

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    mas985's Avatar
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    Re: Differences in Salt Level Readings

    The Taylor kit is good only to +- 200 ppm so those results are consistent except maybe for the last one but that could just be a test error.

    As for the SWG, many have reported that the IntelliChlor does not compensate properly for water temperature change. If you measure the water temperature at the same time as the SWG salt measurement, you will probably see the salt level go up with water temp and visa versa.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Mod Squad pooldv's Avatar
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    Re: Differences in Salt Level Readings

    Yes, salt reading definitely varies with temp on the Intellichlor. We are on season 5 with ours and gave up long ago trying to hit a number. We are just looking for all green lights. The good news is that it will not give any errors when it thinks salt is between 2800 ppm and 4500 ppm. So, we have a big easy target to hit. Aside from that we love our IC40.
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    Re: Differences in Salt Level Readings

    Quote Originally Posted by mas985 View Post
    The Taylor kit is good only to +- 200 ppm so those results are consistent except maybe for the last one but that could just be a test error.

    As for the SWG, many have reported that the IntelliChlor does not compensate properly for water temperature change. If you measure the water temperature at the same time as the SWG salt measurement, you will probably see the salt level go up with water temp and visa versa.
    Mark: I feel confident that I eliminated the possibility of a test error with the Taylor kit on July 18. I repeated the test twice more & got the same reading. 'Tis perplexing.

    Thanks for the suggestion to note the water temperature when I take the SWG reading. Will do.
    Kit
    14' X 11' rectangular in-ground spa; 2,360 gals; plaster/gunite; SWCG (Pentair IntelliChlor); Pentair Intelliflo varaible-speed pump; EasyTouch4 control system; cartridge filters; auto cover

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    Re: Differences in Salt Level Readings

    Quote Originally Posted by pooldv View Post
    Yes, salt reading definitely varies with temp on the Intellichlor. We are on season 5 with ours and gave up long ago trying to hit a number. We are just looking for all green lights. The good news is that it will not give any errors when it thinks salt is between 2800 ppm and 4500 ppm. So, we have a big easy target to hit. Aside from that we love our IC40.
    I think that I am being a bit anal about targeting the salt level to a specific number. (I'm a new spa owner!). Since I try to monitor the TC daily & the FC weekly, problems associated with too little (or too much) chlorine shouldn't be an issue.

    Also, after 4 months since the IntelliChlor was installed, I cleaned the cell. No visible deposits prior to cleaning; and no foaming when I poured in the acid/water mixture. So I feel confident that I am not getting any spurious SWG readings from a dirty cell sensor.
    Kit
    14' X 11' rectangular in-ground spa; 2,360 gals; plaster/gunite; SWCG (Pentair IntelliChlor); Pentair Intelliflo varaible-speed pump; EasyTouch4 control system; cartridge filters; auto cover

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    Re: Differences in Salt Level Readings

    Avoid cleaning the cell if it doesn't need it. The coating on the blades in the cell is essential to the operation of the unit. Acid will eventually eat this coating and shorten the lifespan of the unit.

    If you are on top of your water chemistry and monitor CSI ranges as recommended on this site, you should never need to clean your cell.

    The actual salt level really isn't that important unless it is too low or too high for the cell to operate. This is a very wide range on most cells, Pentair included.
    -Brian-
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    mas985's Avatar
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    Re: Differences in Salt Level Readings

    I think that I am being a bit anal about targeting the salt level to a specific number. (I'm a new spa owner!).
    I would not disagree but as long as the SWG is happy and does not say the salt level is too high or too low, it really doesn't matter.


    Mark: I feel confident that I eliminated the possibility of a test error with the Taylor kit on July 18. I repeated the test twice more & got the same reading. 'Tis perplexing.
    It is impossible to eliminate error because it is built in to the test method. Each drop is 200 ppm and you don't know if the true salt level is between the last drop or the next drop. The only thing you have done is to make the test repeatable but accuracy and repeatability are two different things.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Differences in Salt Level Readings

    Quote Originally Posted by bdavis466 View Post
    Avoid cleaning the cell if it doesn't need it. The coating on the blades in the cell is essential to the operation of the unit. Acid will eventually eat this coating and shorten the lifespan of the unit.

    If you are on top of your water chemistry and monitor CSI ranges as recommended on this site, you should never need to clean your cell.

    The actual salt level really isn't that important unless it is too low or too high for the cell to operate. This is a very wide range on most cells, Pentair included.
    Thanks, Brian. As soon as I poured the acid mixture into the cell & saw that there was no foaming action, I immediately dumped the mixture & rinsed out the cell.
    Kit
    14' X 11' rectangular in-ground spa; 2,360 gals; plaster/gunite; SWCG (Pentair IntelliChlor); Pentair Intelliflo varaible-speed pump; EasyTouch4 control system; cartridge filters; auto cover

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    Re: Differences in Salt Level Readings

    Quote Originally Posted by mas985 View Post
    It is impossible to eliminate error because it is built in to the test method. Each drop is 200 ppm and you don't know if the true salt level is between the last drop or the next drop. The only thing you have done is to make the test repeatable but accuracy and repeatability are two different things.
    I agree, Mark. But it still seems odd that the drop test had a discrepancy of 600ppm from the same test on the previous day & a 950ppm discrepancy from the SWG from the previous day. Nevertheless, I agree with the comment that if the salt level remains within the range that illuminates the green light, all is good with the world.
    Kit
    14' X 11' rectangular in-ground spa; 2,360 gals; plaster/gunite; SWCG (Pentair IntelliChlor); Pentair Intelliflo varaible-speed pump; EasyTouch4 control system; cartridge filters; auto cover

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