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Thread: Free Chlorine = 0

  1. Back To Top    #1
    tejensen's Avatar
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    Free Chlorine = 0

    Hi,

    Thanks in advance for any information you can provide. Great site, so glad I found it! I read the pool school posts several times and browsed the forum quite a bit. This seems to be a relatively common problem, but would like some specific help. Sorry if this is too long, but want to get as much info out there as possible.

    Quick background: I have had an AG pool my entire life. My parents used HTH granular chlorine (added however much every night by dissolving it in a bucket) and nothing else ever for like 20-30 years and never had any pool problems. I installed my pool about 5 years ago and have been using trichlor in a chlorinator (sure wish someone would have told me that it adds CYA!), "shocking" weekly, algecide, etc... thanks pool store! I have not had any major problems, except for very minor green algae spots from time to time, but was always able to control it with "shock." Unfortunately I do not know what any of the levels were when I winterized the pool in the fall.

    This year I opened the pool and it was decent looking. I added some water, "shocked" it with the 3 one pound bags like always and all was good. Fired up the filter, filled the chlorinator with trichlor and was set. After like 12 hours of filtering it was crystal clear and beautiful. I tested (strips at the time) and all the levels were within range, except the free chlorine. I turned up the dial in the chlorinator and nothing. Have been to the pool store a few times and everything seems fine except low chlorine. I have had to adjust the PH or alkalinity slightly here and there using backing soda or borax, other than that all was fine. I've tried shocking, bought a new chlorinator, some other non-chlorine shock (potassium, maybe?) and can not get the free chlorine to register on the test strip. I even bought a new bottle of strips in case that was the problem.

    About 2 weeks ago (when the 100 degree days started) I was out of town for 5 days. My dad stopped over on the 2nd day to take the filter apart, clean it and recharge with DE because the pressure was starting to rise a bit higher than I liked and I did not have time to get to it. He did that and said everything was fine. I got home 3 days later and the pool literally looked like pea soup. I added more "shock" and filtered / backwashed for about a day and a half and the water was back to crystal clear and beautiful, but still no FC. At this point I was getting tired of the pool store so I google'd the problem and luckily I found this site. I ordered the TF-100 test kit and it arrived yesterday.......

    Last night I tested the water at about 9pm (filter had been running for about 2 hours at that point - timer is set for 4 hours in the am and 4 in the pm.) I did each test a few times to make sure I was doing it correct and could get repeatable results and overall I think I was doing everything ok. Results from this test are:

    TC: 0.5 (From the Taylor Basic Kit (Blue Box)
    PH: 7.2
    FC: 0.5
    CC: 2.0
    TC (Calculated) = 2.5 (not sure why the difference to above TC?)
    TA: 120
    CH: 180
    CYA: >100 (based on the exponential looking scale on the C.A. View Tube I would estimate about 150 - was concerned that this was incorrect so i did this test about 4 times and repeated so assuming its correct. Interestingly, the pool store tested my water on Sunday and told me the CYA was 85!) (EDIT - I forgot about the extended test kit instructions to dilute the sample with tap water and double the reading... will try that tonight and post results.)
    Water Temp: 81F

    After I tested, I planned to shock the pool to see what happened overnight. I did not have enough bleach to shock to the level required based on CYA (>50 I would assume) so I added about 4.5 gallons of 6% which I thought would get me to FC of about 17. I realize that this would likely not help the situation much, but at least I could get an idea of what was going on. I waited about 30 minutes and tested again:

    TC: >5 (From the Taylor Basic Kit (Blue Box)
    PH: 7.2
    FC: 16.5
    CC: 3.5
    TC (Calculated) = 20
    TA: 130
    CH: 180
    CYA: >100
    Water Temp: 81F

    This morning I tested again at 5:30 am:

    TC: 0 (From the Taylor Basic Kit (Blue Box)
    PH: 7.2
    FC: 0
    CC: 3.5
    TC (Calculated) = 3.5
    TA: 130
    CH: 180
    CYA: >100
    Water Temp: 80F

    My diagnosis is that I have a mess on my hands even though the water is beautiful and crystal clear! I'm assuming that I need to dump quite a bit of water and refill to get the CYA somewhere in a workable range... probably 1/2 or more of the total volume? Without doing this step first, I would likely need hundreds of gallons of bleach and then would need a ton to maintain as well. Once I get that in range will need to shock it heavy to get rid of the CC, then balance PH, TA, etc. Once I get it in order I assume that will need to add bleach every night as maintenance dose to keep FC in proper range for new CYA level (going to ditch the chlorinator / trichlor except for times when no one will be home to maintain)? Does this seem to sound right, or am I way out in left field?

    Thanks for reading this far! Again any help would be greatly appreciated.
    Tommy
    Above Ground (24' Round) 15,000 Gallons
    Hayward DE Filter (EC-40) with 1HP Pump - Advertised flow rate = 40 GPM
    Pools receives full sun for majority of the day
    TF-100 Test Kit
    Was using Trichlor with an inline chlorinator, but switched to BBB last year and water has been perfect ever since! (after draining 75% of the water to get rid of the bonus CYA that the Trichlor provided!) Thanks TFP!!!!

  2. Back To Top    #2
    Richard320's Avatar
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    Re: Free Chlorine = 0

    For the CYA, dilute the sample 50-50 with tap water (it has no CYA), mix it good, then use that mixture with the CYA reagent and see what you get. Double it. That will enable you to get a coarse estimate of how much water you need to replace to lower CYA.

    For chlorine: if you're using the FAS-DPD test, don't even waste time with the color block. That's for later on in the season, after the pool is tamed, and you just want to do a quick check.

    Given the high loss overnight, I agree with your assessment that you need to shock. To lower CYA to something usable you''re going to need to drain most of the pool, I'm guessing. With the liner, you might need to do it in two steps, which wastes some water, but keeps the liner from shifting.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

  3. Back To Top    #3
    Butterfly's Avatar
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    Re: Free Chlorine = 0

    Hi Tommy and welcome to the forum

    Great diagnosis Yep, replace water and get that CYA under control.

    Do the 50/50 dilution test Richard mentioned to give you a better idea of how close to 100 you are.

    The only change to your order is to have your pH in the low 7's(and TA adjusted if it is below 50) before starting the shock process.
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

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  4. Back To Top    #4
    tejensen's Avatar
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    Re: Free Chlorine = 0

    Thanks very much. As soon as I posted, I remembered the extended test kit instructions.... I'll check the CYA again tonight and get a more accurate reading. Thanks!
    Above Ground (24' Round) 15,000 Gallons
    Hayward DE Filter (EC-40) with 1HP Pump - Advertised flow rate = 40 GPM
    Pools receives full sun for majority of the day
    TF-100 Test Kit
    Was using Trichlor with an inline chlorinator, but switched to BBB last year and water has been perfect ever since! (after draining 75% of the water to get rid of the bonus CYA that the Trichlor provided!) Thanks TFP!!!!

  5. Back To Top    #5
    linen's Avatar
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    Re: Free Chlorine = 0

    Hello tejensen,

    I agree nice job diagnosing your problem! Not the typical first post I have seen when people have a problem.

    Butterfly,

    I have a quick question. In your response to the OP you said:

    Quote Originally Posted by Butterfly
    (and TA adjusted if it is below 50) before starting the shock process.
    Trying to learn here...so...why do this before shocking?
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

  6. Back To Top    #6

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    Re: Free Chlorine = 0

    I'm definitely NOT an expert on pools, but from what I understand you have a couple of options for draining a vinyl pool.

    1. You can drain until there is about 6-8" of water remaining in the shallow end, and you're liner should remain wrinkle free.

    2. You can buy a tarp that is about 20' longer and wider than your pool. So, if your pool is 20'x40', get a 40'x60' tarp. Float the tarp on top of the pool and add water with a hose on top of the tarp while at the same time drain the water from underneath the tarp. To drain the water from underneath the tarp, you would set your valves so you are only sucking water from the main drain and set the filter to waste. Using this option, you will drain much quicker than you fill, so I would guess you only run your pump for about 10 minutes every hour, while continuously filling your pool.
    20'x40' Oval 27,000 gallon Vinyl IG, Coverstar Auto Cover
    Hayward MaxFlo SP2303VSP, Sta-Rite PLD50 30 sq. ft. DE filter
    Rheem 266,000 btu natural gas heater
    Dolphin Nautilus Plus with Clever Clean
    TF-100 testkit w/ Speed Stir

  7. Back To Top    #7
    tejensen's Avatar
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    Re: Free Chlorine = 0

    Just want to thank everyone and apologize for not getting back quicker. Over the past few weeks, I ended up draining and refilling about 3/4 of the water in the pool twice and now everything is great. CYA came down to the 70 - 80 range and CC = 0 - 0.5. I've been adding about 1/2 gallon of 6% bleach per night and the water is perfect. I even ordered the test strips and bought the supplies to adjust the borate level. I can't imagine it getting any better, but I know it can't hurt! I'll have to remember to take a picture of the pool if it ever stops raining!

    I do have two questions. (If I should post these questions under a new thread/subject let me know)

    First is about solar covers... now that the evenings are getting cooler I was thinking of getting a solar cover... do they actually work well? Any suggestions on brand or place to purchase? My second question is if anyone has any recommendation on winter covers (would like a leaf net too after reading about them)? The ones I have been buying locally are cheap and only last 2 - 3 years. Any suggestions on these either? Brands / types / dealers / discounts (I just donated to the site tonight... I didn't even notice that button up top until now.)

    Thanks
    Tommy
    Above Ground (24' Round) 15,000 Gallons
    Hayward DE Filter (EC-40) with 1HP Pump - Advertised flow rate = 40 GPM
    Pools receives full sun for majority of the day
    TF-100 Test Kit
    Was using Trichlor with an inline chlorinator, but switched to BBB last year and water has been perfect ever since! (after draining 75% of the water to get rid of the bonus CYA that the Trichlor provided!) Thanks TFP!!!!

  8. Back To Top    #8
    Mod Squad Bama Rambler's Avatar
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    Re: Free Chlorine = 0

    Solar covers are definitely worth the trouble and expense. I use one a lot during the fringes of the season. I bought mine from solarcovers.com but lots of places have them. I also recommend a reel. It makes life a whole lot easier donning and doffing the cover. You want to stay with a 8 or 12 mil cover. The 16 mil covers (IMO) are too heavy and don't improve the heat retention enough to warrant the extra weight and expense.

    2 to 3 years for a cheap cover that sits out in the elements all winter is pretty good. I just buy the cheapest one I can find and figure on replacing it every couple of years.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

  9. Back To Top    #9
    tejensen's Avatar
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    Re: Free Chlorine = 0

    Great, thanks for the info.

    Tommy
    Above Ground (24' Round) 15,000 Gallons
    Hayward DE Filter (EC-40) with 1HP Pump - Advertised flow rate = 40 GPM
    Pools receives full sun for majority of the day
    TF-100 Test Kit
    Was using Trichlor with an inline chlorinator, but switched to BBB last year and water has been perfect ever since! (after draining 75% of the water to get rid of the bonus CYA that the Trichlor provided!) Thanks TFP!!!!

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