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Thread: Interpreting test numbers

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    Interpreting test numbers

    Need some help here...I have a 15' x 42" Easy Set pool. Water is about 28" deep. I am going crazy looking online for answers to what I need to do to keep the pool safe/clean/balanced!

    I put in a 1 lb. hth Shock 'N Swim package (Walmart) tonight as I kept getting reading of 0 FC on my test strips. I have been running the pump for 2 hours since then and went to check it and the water is completely cloudy. The test strip shows FC 2, PH 7.8, TA 240.

    I need some help interpreting these numbers. How bad is it?!

  2. Back To Top    #2
    JasonLion's Avatar
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    Re: Interpreting test numbers

    Welcome to TFP!

    Do you know what your CYA level is? Have you added any CYA since the pool was filled?
    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: Interpreting test numbers

    I don't have a test that can tell me the CYA level but I can tell you that I added about 10 oz. of HTH Stabilizer and Conditioner a couple of days ago. That was the dosing amount that came with the the pop up pool starter kit I purchased.

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    frogabog's Avatar
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    Re: Interpreting test numbers

    Do you have Intex's volume information for your pool? The shape of those makes it more difficult to do a simple width x water height calculation but Intex has the information on their website and it should have been in the pool manual as well.

    Using that number at the top of the pool calculator, scroll to the bottom you can enter in the 10oz of stabilizer in the "effects of chemicals" field and it should tell you the approximate value of CYA ppm.

    Then, recount how many packets of "shock" product (the powder) that you have added to the pool. The value for that will be found using "dichlor" selection in the calculator. You will need to add this value to the calculated CYA value from above.

    This will give you a general idea of the CYA level for now. If you could report back with that value, it will help us help you.

    2ppm is ok if you have NO CYA in the pool. This isn't your case. If you have 20ppm CYA, 2ppm chlorine is your minimum. If CYA is 30ppm, 2ppm chlorine is under minimum and algae will bloom eventually at that level. If CYA is 30ppm, you'll need to start the day with 7ppm chlorine, and expect to end up at 3-4ppm at the end of the day, but no lower.

    I would suggest that you cease all powdered chlorine for now, until you know the CYA level. It can take up to a week for stabilizer to register on the tests, so calculations based on additions are your best option for the time being. Switch to only using 6% bleach and use the calculator to determine how much to add to bring the pool up to the target level for your CYA ppm. You will need to add bleach daily (at night, after swimmers are gone) taking chlorine to the target in preparation for the next day's use. When all is well, your pool should only need ~1cup of bleach a day or less. My pool is roughly twice the size of yours, and I use 2-5 cups daily depending on sun/rain/swimmers. Yesterday with close to an inch of rain (rare!), clouds all day, plus 1hr of 4 swimmers, I only needed two cups at the end of the day to raise chlorine two ppm up to my target of 7ppm. Sunny swimming days, I loose more and usually have to dose ~3ppm at night. Hope that helps you get a feel for what to expect once you switch to bleach only.


    Now, with all that said... it is my opinion that even small pool owners should have a good test kit, so I would suggest that you consider purchasing one. Pool water chemistry is no different for small pools than it is for large pools. Strips are junk and will set you to chasing your tail all summer. I would never use them again personally unless I was bored and wanted a good laugh comparing my test results to the strip's.
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
    Year 3 BBB -15' x 48" Intex Metal Frame - Was using (2) 1000gph Intex cartridge filters (see Full time pumping Intex). 2012, converted to 1600gph and sand filter+SWG = Sand filter love affair!
    Don't waste time and energy looking for a better value on test kits, the TF100 is the best deal around. I did the looking and spent the extra money, but you don't have to make the same mistake. Just go here: TFTestkits. I use Pool Calculator for min/max, and shocking chlorine levels.

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    Mod Squad JohnT's Avatar
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    Re: Interpreting test numbers

    That should make your CYA around 20ppm. Most likely the cloudiness is a result of the cal-hypo shock that you added. The pump and filter you have will struggle to keep the water clear when using powdered chemicals.

    I'd recommend you shock your pool by adding about half a gallon of 6% bleach to the water. If you get your CYA up around 30-35 by adding another 4-6oz of stabilizer, you can probably maintain good chlorine levels with around 2 cups of bleach morning and evening, depending on what your testing shows.
    TFP Moderator
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    frogabog's Avatar
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    Re: Interpreting test numbers

    Oops, nevermind all that about the shock product that I said earlier. I was thinking shock n swim was dichlor. Haven't used it in a long time, sorry.
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
    Year 3 BBB -15' x 48" Intex Metal Frame - Was using (2) 1000gph Intex cartridge filters (see Full time pumping Intex). 2012, converted to 1600gph and sand filter+SWG = Sand filter love affair!
    Don't waste time and energy looking for a better value on test kits, the TF100 is the best deal around. I did the looking and spent the extra money, but you don't have to make the same mistake. Just go here: TFTestkits. I use Pool Calculator for min/max, and shocking chlorine levels.

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    Re: Interpreting test numbers

    So....are you telling me that if I get the CYA at the right level that I can manage the rest of the levels (pH, chlorine, alkalinity, etc.) with just 6% bleach?? Can I just "switch" types of chlorination like that or do I need to do anything special first?

    I think I have purchased every possible pool chemical available to man and I am about to drain the darn thing and be done with all of it! I'm finding this to be too much work (and expense!) for something that is supposed to be fun! I know I need a good test kit but can't bring myself to spend another $70 when I have ALREADY spent more in the chemicals to maintain the darn thing than I did on the pool itself!!

    Thanks for the help you have offered. I must be making this more complicated than it really is!

  8. Back To Top    #8
    frogabog's Avatar
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    Re: Interpreting test numbers

    No, you can't adjust PH and alkalinity with chlorine (bleach), but the chemicals to adjust ph and alkalinity are common household items (baking soda, 20/20 mule team) and muriatic acid which one might have in the garage. PH down is dry acid, an alternative to muriatic acid but a little more expensive.

    The point really is that out of the chemicals the pool store sells you, the only ones you actually need are the exact same as you find in the grocer and hardware store. All the other stuff, the algaecide and sparkly pool goo of various sorts are unnecessary.

    The other point is, once you get your water balanced all you will need daily is chlorine. Some pools have fast rising ph, so a weekly dose of muriatic acid is also added to the soup. But many of us only have to add bleach all season once the water is balanced. There is the occasional ph drift to adjust, and maybe if it rains a lot or something gets into the pool, or a lot of water is drained/added will there be the need to re-adjust.

    Knowing and targeting an appropriate CYA level for your pool is where you start, effectively setting the pool at a certain platform from which you can control the chlorine levels easily. Without CYA, ALL your chlorine will burn off by sun and bathers every day. Your pool will drop to 0, and that is not good because things will grow. With a lot of CYA, most of the chlorine in the pool is inactive and bound up under sunscreen which means you have to make sure it's all there under the sunscreen, plus add enough atop that level to actively disinfect. If you drop below the inactive level, it starts using all that inactive chlorine and will eat it up fast. And this is when again, things start to grow.

    At a moderate CYA level (let's say 40ppm), your inactive chlorine is in the 1-3ppm range. Always there, always inactive. From 3-7ppm the chlorine is active, killing stuff, and allowed to burn off via sun. Every day you re-dose up to 7ppm, sleep, wake, swim, sunbathe... and end up at the end of the day still above the inactive level. This allows you to never fall below minimum (3ppm), and always have chlorine in the pool no matter if you use all your active chlorine every day, or not.

    CYA is your sunscreen, disinfection safety net, and protector for your chlorine. And like any good thing, too much is trouble.
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
    Year 3 BBB -15' x 48" Intex Metal Frame - Was using (2) 1000gph Intex cartridge filters (see Full time pumping Intex). 2012, converted to 1600gph and sand filter+SWG = Sand filter love affair!
    Don't waste time and energy looking for a better value on test kits, the TF100 is the best deal around. I did the looking and spent the extra money, but you don't have to make the same mistake. Just go here: TFTestkits. I use Pool Calculator for min/max, and shocking chlorine levels.

  9. Back To Top    #9

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    Re: Interpreting test numbers

    Other than Cya you can manage the pool with just Bleach, Borax and Baking Soda and muiritic acid and yes you can switch types of chlorine and you don't need to do anything first .

    A good test kit is not an option it is mandatory to take care of a pool not having a good test kit is what is making it complicated without one you just can't tell what to add.
    Steve Frakes
    15' X 48'' Intex Metal Frame
    Intex Sand Filter 16'' 2650 GPH
    Taylor K-2006 Test Kit
    BBB and Borated

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    Isaac-1's Avatar
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    Re: Interpreting test numbers

    I know it is hard to justify spending lots of money on a test kit after wasting money on pool chemicals, but it really will save you money in the long run. If you just can't budget the TF-100 now, get the TF-50 it is a smaller version of the same kit but without the OTO/pH kit plus buy the cheap OTO/pH kit from Wal-Mart, it is less bang for the buck, but probably enough test reagent to get you through the end of this swim season if nothing goes wrong. You probably want to also get rid of the test strips they are more headache than they are worth, and if you use them you will probably just end up wasting money on chemicals you don't need due to inaccurate readings. We have all been there and know the last thing you want to hear now is you need to spend more money. But if you can justify it go ahead and put down the extra $20 for the TF-100, as it gives you double or more of the test reagents compared to the TF-50 plus the OTO/pH kit.
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
    I use and endorse TFtestKits TF-100 from http://tftestkits.net
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