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Thread: Is My FC Really 40+?

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    Is My FC Really 40+?

    I got my FAS test kit today and tested my water. I know that the water has a high chlorine level after recently battling green algae. However, the FAS test resulted in a chlorine level of 40+!

    The first time I tested, I used one heaping spoon full. I did not believe the results of 40+ppm, so I retested. The second time I used 2 level scoops, but the results were the same, 40+ppm.

    Is this real?
    22K gallon in ground, vinyl lined pool
    Sand filter (zeo-sand)

    Jeramie

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    Re: R-0870 The Dipper??

    It could be what have you been adding to the pool? Can you post a full set of tests?
    12,300 Gallon, IG PebbleFina, 3 ft sheer, 2 Jandy nicheless LED lights, Jandy Pro 1.5HP VS pump (A.O. Smith Motor), PB4-60 Booster pump, Polaris 280, Jandy cv340 cartridge filter, Zodiac Z4 control panel W/iAquaLink, Stenner pumps for chlorine & MA connected to WiOn WiFi switches, TF-100. You can support TFP with AmazonSmile just click the link!

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    Re: Is My FC Really 40+?

    What size sample did you use - 10ml or 25ml? And how many drops did you add?

    Were you holding the reagent bottle completely vertical and letting the drops fully form on the tip (about 1 second between drops)?
    Gene
    ​12,300 gal IG play pool - Pebbletec - built 10/1999 || Hayward S360SX 36" sand filter || Hayward Ecostar SP3400 VSP || A&A In-Floor cleaning system || Quik Water Leveler || Quik Dek-clor (limited use)
    TF-100 testkit / Speedstir - A good test kit is not an expense, it's an investment

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    aussieta's Avatar
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    Re: Is My FC Really 40+?

    also do not allow the test to sit or it will go pink again
    as mentioned one drop per second and when it goes clear that is the end
    SWG inground peanut shaped eco-bright concrete pool
    50,000 litres 13,000 gallons
    Lincoln Salt Chlorinator, 25 gram cell Sand Filter with glass media
    Taylor K2006-C test kit, Taylor K-1766 salt test, Dolphin M500 pool cleaner
    are you taking care of your pool or is the poolshop taking care of you

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    Re: Is My FC Really 40+?

    I just retries the measurements with the same 40+ results. I tried 2 times this morning, one with 2 level scoops and the other with 2 rounded scoops

    I held the reagent bottle vertical

    10mL sample size
    FC 40+
    pH: cannot measure due to high chlorine
    TA: 90
    CH: 260
    CYA: 50

    22K gallon in ground, vinyl lined pool
    Sand filter (zeo-sand)

    Jeramie

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    Re: Is My FC Really 40+?

    tell us why you think it is not correct. How much chlorine have you been putting in your pool? Is this the first time you have ever measured chlorine?

    There is no point doing the test over and over.....unless you change something you will get the same result.

    The FAS/DPD test you are using is extremely accurate so I think the answer is "yes, it's real".

    Now we have to figure out how you got there.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: Is My FC Really 40+?

    I was shocking heavily to get rid of algae over the past week.

    Now, how do I lower the chlorine?

    22K gallon in ground, vinyl lined pool
    Sand filter (zeo-sand)

    Jeramie

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    Re: Is My FC Really 40+?

    Quote Originally Posted by HateMyPool View Post
    Now, how do I lower the chlorine?
    Waiting game. Time and UV rays will do it. Sunny and hot on the east coast next few days. It won't take long for the sun to eat it up.

    And just to clarify, with the 10ml sample you are adding 80 drops of R-0871 to go from pink to clear? Resulting in an 80 x 0.5 = 40 to get your 40 reading? You are not adding 40 drops and calling that your FC reading right? Apology if that is being very sophomoric but just checking a simple common mistake first.

    And FYI, the exact amount of powder (R-0870) that you use is not critical. The Powder is an indicator, the R-0871 is a reagent. Generally speaking when doing titration tests, indicators don't have to be so precise, but reagents do.
    25 + year pool owner. Current pool (going on 11th year) - 38K gallon in ground Gunite/White Plaster, Spillover Spa, Hayward Cartridge Filter, Hayward 450k BTU NG Heater, Hayward Goldline Aqua Logic control with T-Cell-15 Salt Water Cell, Dolphin Explorer.
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    Re: Is My FC Really 40+?

    Quote Originally Posted by HateMyPool View Post
    I just retries the measurements with the same 40+ results. I tried 2 times this morning, one with 2 level scoops and the other with 2 rounded scoops

    I held the reagent bottle vertical

    10mL sample size
    FC 40+
    pH: cannot measure due to high chlorine
    TA: 90
    CH: 260
    CYA: 50

    Sent from my SAMSUNG-SM-G930A using Tapatalk
    So, just to be clear, you got that 40ppm by using the 10ml sample size, and 80 drops of R-871 reagent, correct?

    Dom
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    Re: Is My FC Really 40+?

    Correct. 80+ drops of the reagent

    22K gallon in ground, vinyl lined pool
    Sand filter (zeo-sand)

    Jeramie

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    Re: Is My FC Really 40+?

    Well looks like you are going to have to wait a couple of days.
    I would not bother testing today let the sun do it's job test again tomorrow and see where you are at, as soon as it drops to around 20 ppm or below it is safe to swim assuming the water looks good. In the mean time if you have not had a chance take a look at the PoolShcool link under solving problems/defeating algae/ and read the directions for SLAM. With any luck you should be mostly done with SLAM even if you did not know that was what your were doing. You will know for sure when you preform the OCLT steps described in the process. If you don't pass OCLT you want to hold the FC around 20ppm until you can pass the test, even if the water looks good otherwise the algae can come back. Once you pass the OCLT you want to let the FC drop to between 4 & 6 ppm and hold it there indefinitely that's the correct level for your pool based on your CYA derived from THIS chart.
    12,300 Gallon, IG PebbleFina, 3 ft sheer, 2 Jandy nicheless LED lights, Jandy Pro 1.5HP VS pump (A.O. Smith Motor), PB4-60 Booster pump, Polaris 280, Jandy cv340 cartridge filter, Zodiac Z4 control panel W/iAquaLink, Stenner pumps for chlorine & MA connected to WiOn WiFi switches, TF-100. You can support TFP with AmazonSmile just click the link!

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