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Thread: Drained Pool - Different test results now - How to start?

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    Drained Pool - Different test results now - How to start?

    Since my CYA was 180 I followed the advice from my previous thread and drained about 70% of my pool yesterday. It is being running for about 5 hours and I decided to test it myself using my new TF-100 test kit and also took it to Leslie's and the Warehouse Pool Supply to validate my test. Guess what - got 3 different test results.

    TF-100 - First time testing
    FC = 0.5
    CC = 0
    TC = 0.5
    TA = 250
    CH = 210
    CYA = 65 (I tested yesterday before draining and it was way over 100)
    PH = 7.8

    Leslie's
    FC = 0
    CC = 0
    TC = 0
    TA = 240
    CH = 260
    CYA = 35
    PH = 7.6

    Warehouse Pool Supply
    FC = 0.2
    CC = 0
    TC = 0.2
    TA = 175
    CH = 165
    CYA = 110 - They told me to drain again
    PH = 8.2


    I don't feel like draining again so I think I will trust my test and Leslie's. What do you think?

    I am not sure how to get started with the BBB since I am getting different recommendations:
    Leslies: Add 1 gallon and 1/2 of Acid and also 2 pounds of shock
    Calculator: Add only 45oz of Acid and 152oz of bleach


    Why is the calculator so off from Leslie's on the Acid? Should I follow the calculator only or do something else? Remember that I had algae starting to form before I drained.

    Thanks a lot! I really appreciate it.
    21K gal, blue color plaster, DE filter

  2. Back To Top    #2

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    Mr.d - while I followed your other thread, the others gave any answer I might have, so I just kept my mouth shut -- welcome to TFP!

    Someone, if not everyone, is doing one or more of the tests wrong/ or using a BS tester! (Evan is VERY good at this stuff so maybe he can tell who is making the mistake and where) While we usually advise people to trust their own tests, there are a few places that a 'first time tester' may make some mistakes Given your and Leslie's tests being almost within the 'margin of error' for the tests, I'd go with them rather than the WPS #s.

    I can't presume to speak for Jason nor his calculator - but I'd say that Jason's calculator takes into account the other parameters of the water while the Leslie's guy is just reading off of a chart for the amount of 'chemical X' to add to get any of the individual #s 'up to par'.

    You are on the right track by coming here to learn about how to properly care for your pool! and by not trusting the pool stores to give you the correct advice/ knowledge.

    If you have any questions on using your GREAT test kit - ask them, and Dave, Evan, myself and quite a few others will help with testing techniques so that you can accurately and successfully use your kit


    {Dave and Evan - I think it would be GREAT if you guys teamed up to provide a 'sticky' on using drop based test kits}
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

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    MrDaniel,

    Put your faith in the advice and calculations (and testing) on this forum.

    Tell us something first....How does your water look? If it's crystal clear, we'll recommend one path.....if it's green or murky, we'll go down another road. Use Jason's calculator for your calcs, and, there's an axiom on this forum.....Trust your own test results!!
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    The water is crystal clear and looks awesome.

    I haven't used the calculator much before but it looks like it is only making recommendation to bring my PH from 7.8 to 7.5 and not doing anything on the TA.

    If I change the PH to 7.5 and leave TA to 250 it does not recommend anything.

    The calculator does have the message: To lower TA you reduce PH to 7.0-7.2 with acid and then aerate to increase PH. If I tell the calculator to lower my PH to 7.0 it will tell me to use 184oz of acid which matches Leslie's. But I am not sure how to aerate the pool to increase the PH and not change TA again.

    So I am not sure what to do here. I've just added 32oz of acid since I think I need at least some.

    Thanks again.
    21K gal, blue color plaster, DE filter

  5. Back To Top    #5
    JasonLion's Avatar
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    Trust your own testing. You are in the middle of the two pool store tests, which means you did the tests correctly. The two stores differ from each other by more than they should, but that is common enough.

    My Pool Calculator can tell you how much of a chemical to use to make some specific change, but it won't tell you what change to make. You need to know what you are trying to achieve and enter that into the goal column.

    First priority is to add some chlorine. With CYA of 65 you want FC to be between 5 and 10. I suggest aiming for 8 in the evening and seeing where it ends up the next evening. If it falls below 5 then you will want to aim higher. The basic routine is to test the FC level and then add enough bleach to bring it up to 8 each evening. To bring FC from 0.5 to 8 in 21,000 gallons you will need just over 2 and 1/2 gallons of 6% bleach, which is about the same as the 2 lbs of shock that Leslie's recommended. Tomorrow you will probably need much less, since you won't be starting from zero.

    Next you want to adjust the PH. With high TA you can expect the PH to creep up fairly quickly. You will need to get some experience to see how quickly it rises in your pool. You want to center PH around 7.5. Since it is likely to rise on its own you want to adjust it to lower than 7.5, say to 7.2. That will give you more time before you need to add more acid.

    The basic routine on PH is to wait till it goes up to 7.8 and then lower it to 7.2. To take PH down to 7.2 from 7.8 will take a little under a gallon of muriatic acid. PH changes are approximate, so maybe play it safe and try 3/4 of a gallon (96 oz) and see what happens. If it goes below 7.2 use less next time, if it doesn't make it down to 7.2 then use more next time. The first few times you need to check right away tomorrow to see how quickly it is rising. Once you get a sense of how rapidly it rises you can figure out how frequently you will need to adjust PH.

    Long term you want to lower TA significantly, perhaps as low as 80. Adding acid to keep the PH reasonable will take care of that slowly. If the PH rises too quickly you may want to lower TA more quickly. Lets wait and see on that.
    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

  6. Back To Top    #6

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    So I added 2 and 1/2 gallons of 6% bleach last night (about 9pm)
    and also added 1 gallon and 1/4 of acid - I added the acid in 32oz increments every 2 hours (the Leslie's people told me to only add acid in 32oz increments)

    Here are the new test results as of 6:30pm today - the pump has been running 24x7.

    FC = 7
    CC = 0
    TC = 7
    TA = 230
    CH = 210
    PH = 7.2
    Temperature=68

    Is it normal for the PH to drop from 7.8 to 7.2 and the TA only drop from 250 to 230?

    Per the calculator, I now need to add 44oz of 6% bleach to bring my FC back to 8. Can you please confirm if this all I need to do now until the PH goes back to 7.8? Is it OK to start running the pump for only 6 hours a day until it gets hotter?

    Thanks a lot!
    21K gal, blue color plaster, DE filter

  7. Back To Top    #7
    JasonLion's Avatar
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    Much better!

    Yes, 44 oz of 6% bleach should take care of things till tomorrow.

    Yes, you can cut back the pump run time significantly. I don't know if 6 hours a day is right for your pool or not, but something around there will be fine. Try six hours a day and see what happens. Just be sure that the pump is running for at least an hour after you add chemicals.

    That TA change is about what I would expect.

    There is no real reason to only add 32 oz of acid at a time. You do want to pour acid very slowly in front of a return, but you can keep on pouring the full amount in one go.

    Test the PH every day and let it rise till it gets to around 7.8, then lower it again with acid. As the TA comes down it will take a little less acid each time.
    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

  8. Back To Top    #8

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    Just wanted to post a follow-up after two weeks on the BBB method. It looks like I still have algae, it is growing extremely slowly but I can definitely see some signs of green forming after 1 week of brushing, specially in the spa.

    Following Jason's recommendation, I've been increasing the FC to 8 every night and noticed that it usually drops to 7 the next night. The lowest FC I've seen is 6, but 7 seems to be the average. I've also been adding acid when ph gets high to get the TA down. Running the pump for 6 hours/day.

    Here is my latest test results, at about 10am this morning, using the TF100 and a phosphate test:

    FC = 7.5
    CC = 0
    TC = 7.5
    TA = 150
    CH = 180
    CYA = 60
    PH = 7.5
    Phosphate=1000+ ppb
    Temperature=70

    It looks like my next step is to shock the pool, right? The Pool calculator says I need to increase FC to 18. For how long would you say I need to keep the FC to 18? Do I need to run the pump 24x7 while shocking it?

    Thanks again! I really appreciate it.
    21K gal, blue color plaster, DE filter

  9. Back To Top    #9
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    How recently did you test the CYA? You aren't losing as much chlorine per day as I would expect. Between sunlight and algae I would expect you to lose almost half of your FC each day at a CYA level of 60.

    You want to hold the pool at shock level until the overnight chlorine demand goes away. Test the FC level after sunset and again first thing in the morning. If it is within 0.5 of the same then you are done shocking. While the water is at shock level you need to brush the entire pool every day and run the pump 24/7.
    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

  10. Back To Top    #10

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    I tested everything this morning and got the CYA of 60. Last weekend the CYA was about 60 as well. I also used aquachek test strips to double check and it matches the Ideal color (30-50).

    The Algae is very minimum and I can barely see the green forming in the spa, but I can see it there after brushing a week ago. Do you think there is something wrong with the CYA?

    There was one day I didn't have time to add bleach this week and the day after the FC was at 5.

    These are the FC numbers of the last 2 weeks:
    fri = 5
    wed = 7.5
    tue = 6.5
    mon = 6
    sun = 8
    sat = 7.5
    fri = 7
    thu = 6
    wed = 7.5
    tue = 6.5


    Thanks a lot!
    21K gal, blue color plaster, DE filter

  11. Back To Top    #11

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    The water is crystal clear and looks awesome.
    I think that post you made back a couple of weeks ago caused everyone to overlook the fact that you had earlier reported algae.

    There's little doubt in my mind that you need to shock your pool. Follow Jason's advice to increase Cl to 18ppm and HOLD IT THERE until your pool is clear or, as he says, your FC holds within .5 overnight. Again, repeating Jason, you must brush everyday and run the pump 24/7.

    You've got that Alk issue but I would address that in a different post at a different time. Dont worry about the CYA, it's fine. Get your algae issues completely cleared up first.

    EDIT - Chlorine does not hold up as well in a spa as a pool because of the higher temps. Have you tested FC directly from the spa? You may have to supplement that a little.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  12. Back To Top    #12
    JasonLion's Avatar
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    If the algae has been there all along then I agree with duraleigh, you need to shock.

    If the algae went away and then reappeared only in the spa, there might be a circulation problem in the spa that is causing the FC level to be lower in the spa than in the pool. You normally want pool water circulating into the spa, which normally means the spa overflowing into the pool, the entire time the pump is on (except for comparatively short periods in spa mode). Having your pump run time significantly too short, or failing to run the pump for at least an hour after adding chlorine could also cause this.
    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

  13. Back To Top    #13

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    The algae was there before draining and since I didn't shocked after refilling I think it has been there all along. The spa is overflowing into the pool the entire time the pump is on and I do run the pump for at least an hour after adding chlorine.

    I shocked ( 18 ) at noon and it is now 5pm and here are my numbers:
    FC Pool = 13.5
    FC Spa = 15.5

    I just added more chlorine to bring the 13.5 to 18 (196oz) and will check again after sunset.

    Thanks a lot for all your help.
    21K gal, blue color plaster, DE filter

  14. Back To Top    #14

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    Don't mean to nag but be sure to brush all the sides and walls during this shock process.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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