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Thread: salt and TDS question

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    reebok's Avatar
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    salt and TDS question

    I had my salt tested at pinch a penny today because I wanted to add some to my non-swg pool for the benefits talked about elsewhere on this forum. I have always had a great experience at pinch a penny and stopped going to leslies a couple years ago because they're such....well anyway. today there was a guy there who I hadn't seen before. I've basically dealt with the same two people for a couple years, but this guy I didn't recognize. so I ask him to test for salt and he says:
    we don't have you as a salt pool, do you know what swg you have?
    me: I don't have one I'd just like to know.
    him: well if you don't have one there won't be any salt.
    me: then you're not doing the test right because lots of stuff adds salt. chlorine...
    him: well yeah but it will be very minimal. I know my chemistry.
    he then puts the water in a little bowl thing on top of some machine (from the back this thing looks a lot like a kitchen scale). it took him maybe a half second to tell me my salt was 1700. I find that pretty significant, esp since that's even higher than I was going to make it by adding salt. not to mention its over halfway to the recommended salt guidelines for most swg's. so how did my salt get so high? is that normal? I wouldn't think so since so many people are adding salt judging from other posts. also, on 4/16 my TDS was 1,110, and today it was 2,700. it's always been around 1,000. what happened in a week to make it go so high?
    I'm going to leslies later on to get another test and that recommended test kit. the rest of my numbers today were:
    FC 4
    pH 7.8 (I've been battling rising pH since the pool was rebult in late 2007)
    TA 119 (same as last week)
    CH 399 (same as last week)
    Stabilizer 75 (same as last week)
    TDS 2,700 up from 1110 last week
    I do plan on running my chlorine to the levels recommended on the chart, but my current test kit maxes out at 3.0 which is why I'm getting the new kit today. I also plan on using about half the recommended dose of PQ60 until it runs out. the pool looks great. thanks for any insight.
    16x32 21,000 gallon in-ground exposed aggregate, 1.5hp pump, 120 sqft catridge filter, birdcage, solar panels, aquavac tigershark qc robot.

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    Join Date
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    San Rafael, CA USA
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    Re: salt and TDS question

    Clearly, your TDS did not actually jump from 1100 to 2700 in one week without adding lots of salt to the pool. There's obviously a big test error. You should get your own salt test to see what is really going on. There's the AquaChek White salt test here that most people use (or the Taylor K-1766 test -- I seem to be the only one who like using this particular test).

    With a cartridge filter one can build up the salt faster since there's no backwashing. On the other hand, if in Florida you get rains that spillover the water in the pool, then you should be getting some dilution. If I ignore dilution and assume you are adding 2 ppm FC per day of chlorinating liquid or bleach, then the salt level (and TDS) increases by around 100 ppm per month.

    Richard
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Oct 2007
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    Valrico, FL
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    Re: salt and TDS question

    The salt meter that Pinch-A-Penny uses is just a TDS meter calibrated to read salt. And a TDS meter is just a conductivity meter. Same basic instrument just different scales. Like most electronic instruments, they need to be calibrated at regular intervals. You might ask when the instrument was last calibrated.

    Pinch-A-Penny takes their testing service and also their customer service very seriously. You might want to sent Pinch-A-Penny corporate an e-mail about the reception you recieved.
    7,500 gal, IG pool, L shape 22' x 15', 1.5 hp pump, cartridge filter, AquaPlus SWG/Controller, Pebble-Tec liner.

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    frustratedpoolmom's Avatar
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    May 2007
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    Re: salt and TDS question

    Just a note...you may not be able to get the kit in stores. Read in Pool School about Test Kits Compared, and then visit the link on the homepage to TFTestkits, or order a Taylor k-2006. I myself have the TF-100 and highly recommend it.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    reebok's Avatar
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    Re: salt and TDS question

    they didn't have it in the store. the pool school article is why I was going to get it, and still may, we'll see. I'm not used to having to order anything for my pool with 3 stores in a 4 mile radius.
    fwiw, leslies results were:
    FC 6
    pH 7.7
    TA 100
    CH 300
    CYA 100
    TDS 2000
    Salt 1800

    so I suppose I am getting the benefits of adding salt to the pool without having to actually buy it. and I couldn't believe how far apart these results were. now I really see why the big push here to get your own kit. I meant to measure my own TA today but forgot. I would like to do borates (found 20 mule team at walmart today...what a weird/obscure product) but lowering TA will be difficult for me, at least until I start swimming more. I have been considering getting the Circulator product which should do the job. thanks for the input.
    16x32 21,000 gallon in-ground exposed aggregate, 1.5hp pump, 120 sqft catridge filter, birdcage, solar panels, aquavac tigershark qc robot.

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