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Thread: Chlorine Testing - Help Requested

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    Chlorine Testing - Help Requested

    I cannot distinguish yellows in OTO test levels 2-5 look the same to me. Any advice? I've seen you are supposed to look in natural light, but it is usually late by the time I get to test. Do you know of other quick tests that are easier to distinguish?

    Can I use a ORP/pH meter instead? I saw one by Hanna instruments that looked simple to use. Do you have an idea how I could relate OPR values to ppm chlorine levels ?
    12,500 gallon vinyl AGP

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    Join Date
    Jan 2009
    Cupertino, CA

    Re: Chlorine Testing - Help Requested

    I can't distinguish the darker yellows either. I don't bother with that test anymore. I use the FAS-DPD test from my TF100 (the Taylor K-2006 also has this) or you can get it separately.

    Don't know about ORP, sorry.
    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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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Chlorine Testing - Help Requested

    Welcome to TFP!

    The inexpensive ORP/pH meters that are available don't last very long. Plus, there is no reliable conversion between ORP and FC. It is possible to use ORP levels to indicate the FC level, but only if you have a recent test from a FC tester to calibrate the ORP meter with, which kinds of defeats the whole point of what you want.

    Many people have problems reading the OTO test above 2. With practice you can figure it out, but it takes quite a bit of time.

    The best test is the FAS-DPD chlorine test. In the FAS-DPD test you count the number of drops it takes to turn the sample from pink to clear. The FAS-DPD chlorine test have a number of other advantages, and is the test most recommended on the forum.
    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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    Re: Chlorine Testing - Help Requested

    Thank you. I am very grateful for the swamp cleaning article. I am using the TF testkit and have been going through titrant big time (I just ordered more). I was hoping for an even quicker way to get a good idea of the chlorine level now that I have a sparkling pool.
    12,500 gallon vinyl AGP

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    Re: Chlorine Testing - Help Requested

    The OTO test is really for a quick daily check of whether there is chlorine or not. Since it is a TC test it doesn't give you much more info than that. The FAS-DPD test should be done weekly as part of your testing schedule and the OTO test done in between as a quick check that there are no problems
    Perhaps this will help:
    Colorless = No chlorine, break out the big kit and figure out why
    very pale yellow = not enough chlorine, break out the big kit and figure out why
    Yellow to dark yellow = yow have chlorine and if your weekly tests are ok you are done
    Orange to bronw = very high chlorine. Unless you are shocking the pool or running a high chlorine pool because of high CYA it's time to break out the big kit and see what's wrong

    Notice that I do this strictly by color and not by numbers. A good way to learn the colors is to do an OTO test each time you do an FAS-DPD test and soon you will learn that when your FC is at your 'normal' range your OTO test is, say, a deep yellow. You now can tell if your chlorine is too low, too high, or in the ballpark on a daily basis from the OTO test. Just remember to do the big test weekly so you can make sure you don't have any CC and to get your exact numbers.

    If you are trying to figure out how much chlorine you need to add daily or every other day use the big test until you know that "my pool needs (fill in correct amount) cups of bleach daily to maintain the level". Then when your chlorine shows low by the OTO test on a daily check add the chlorine. You will be amazed at how close you will be to the right amount. Remember, it's a pool and not a science experiement. While proper testing IS very important it is NOT necessary to micromanage your pool!
    It's not really necessary to use the big kit daily but you should check pH and TC with the small tester at least every few days (daily is best).

    IF you know that there are problems and you are balancing the water don't rely on the OTO test, use the FAS-DPD test.

    OTO is a great tool once you learn how to use it!

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    Re: Chlorine Testing - Help Requested

    Thank you Waterbear. I'll try your recommendations.
    12,500 gallon vinyl AGP

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