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Thread: TF-100 Testing questions

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    TF-100 Testing questions

    After several years of using the test strips from the pool store, and several years of battling algae, I am now the proud owner of a TF-100 test kit. I live in the Chicago area, and I am trying to get a head start on opening our pool even though it's a little cold (pool temp is about 54 degrees). I have several questions about my new test kit though. I am color blind so my wife does all the testing for me.

    1. The CYA test says the water temp should be over 70 degrees. Does the temp matter for any of the other tests? Also, is it ok to heat the water by setting it in front of a space heater or putting it in the microwave? We usually keep our indoor temp at around 68, so letting it sit on the counter will not work.
    2. Just out of curiosity, why does the temp need to be above 70 degrees?
    3. As I said, I am color blind, but my wife is having a real hard time with some of these tests also. For example, on the pH test, the colors range from Yellow(6.8) to Orange(7.2) to light pink(7.5) to darker pink(7.8) to darkest pink(8.2). Our pH reading shows a very very light pink...even a lighter shade than the orange. What is more important, the color or the shade? If the shade is more important, I would say the pH is probably about 6.9, but if it's the color I would put it at about 7.4. I understand that's not a huge range, but it is the difference between adding a little borax to keep me in the ideal range.
    4. I've searched around looking for the answers to my questions, and I've read several opinions on lighting. It sounds like a white background is fairly well agreed upon, but I've seen a lot of opinions on the distance behind the test tube to keep the white background. It seems most people say a shady spot outside is the best place to test, but then there are a lot of people that bring their water samples inside to test. I even saw one mention of the speed stirrer from which stirs the samples and has bottom lit LED's to illuminate the water sample and make reading the colors easier. (Anyone have opinions on this?) I have an LED flashlight, would setting the water samples on the flashlight help us read the color better? We've gotten different results holding the tubes up against our white cabinets vs. taking it outside in indirect light with a white background like a piece of paper 2-3 inches away.
    5. How important is constant stirring? My wife finds it a bit challenging to keep the water rotating, while adding one drop at a time, while holding it against a white background AND finding the *exact* drop that causes the color to change. She says it's kind of like patting her head and rubbing her stomach at the same time.
    30 foot round AGP (25k gal), 2.5 hp pump, Hayward cartridge filter, Diver Dan pool vac, TF-100 Test kit
    -It takes less time to do things right then it does to do it again.

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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: TF-100 Testing questions

    1) For the CYA test only, it is alright to heat the water. The FC and PH tests should be done on the water quickly after it is removed from the pool without any heating. The TA and CH tests don't need to be done right away.
    2) The reaction that produces the white cloudiness in the CYA test proceeds very slowly at colder temperatures, increasing the odds that it has not finished, and the sample is not as cloudy as it will eventually get when you look at the view tube.
    3) All I can say is to practice. Measure your tap water, measure the pool at different levels. It will become more obvious.
    4) Most LEDs are single color light sources, which are not good for doing color comparisons. For indoor use it is best to use a daylight simulator. The LED in the speed stir is not used for the PH test, which requires distinguishing similar colors. Instead it is used for the FC/CC, TA, and CH tests, which just need to show fairly dramatic color changes.
    5) You learn to do it after not too long. Moving the test along quickly can be important if your levels are high. If your levels are lower and the total time isn't going to be all that long then doing each drop more slowly is fine.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida

    Re: TF-100 Testing questions

    Hey, Mike,

    Bring your CYA test indoors and hold it in your grip for a minute or two. It will quickly be 70 degrees.

    As Jason said, You'll get very, very accurate after you do this a time or two. Don't worry about being off by a drop or so. Practice on being consistent.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Join Date
    Jan 2009
    Cupertino, CA

    Re: TF-100 Testing questions

    3) For pH, the color (yellow/orange/pnk) matters, light/dark does not.

    5) Yes, it takes a little coordination. I find it easier to swirl the tube in my right (dominant) hand, while holding the dropper in my left. Looking through the tube at something solid colored (wall, door, sheet of paper) works better than looking down into it, or against a multi-colored background.
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

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