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Thread: How much chlorine will I need (gross numbers)

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    How much chlorine will I need (gross numbers)

    Hi - I've been reading/lurking for a while and finally joined today.

    When my TFP FAS-DPD Chlorine Test kit arrives on Monday, I will start a SLAM to clean up a "green swamp".

    I've been fighting a losing battle for months listening to the pool store -- it's time to do something different.

    My CYA is high -- 90, so I'm going to lower it with a partial drain over the weekend. Get the filter backwashed. Be as ready as I can (anything else I should do?)

    Assuming I went with the CYA level now, I would need to add about 7 gallons to get my FC level up to shock level (35ppm) assuming it's at 5 when I start.

    I'm trying to get a really rough idea of how much chlorine I need to have on hand. Is 20 gallons likely to be enough? 40? More?

    I lowered the PH earlier this week before I started adding chlorine.

    Today's numbers :

    FC 5+ (will know better on Monday)
    PH 7.6
    TA 120
    CH 500
    CYA 90

    We're already into the hot weather in Phoenix, so I need to get through this season and then I'll do a complete drain/refill in the fall.

    Any other advice? Can you tell if I seem to be on the right track? Thanks!!
    25K gal, fiberglass, Hayward 1hp pump, Sta-rite 30" sand filter, Hayward Pool Vac

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    Casey's Avatar
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    Re: How much chlorine will I need (gross numbers)

    You're on the right track. And once you get your CYA under control, you may not need a complete water change unless you CH is up pr your doing a reno. SInce you're doing a drain refill, I'd vac the bottom of the pool to waste to get any sludge out that may be lurking down there.

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    Richard320's Avatar
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    Re: How much chlorine will I need (gross numbers)

    Welcome!

    Sadly, no one can guess exactly how much you'll need. There's no way of knowing how hardy your particular strain of algae is, nor how much is hidden inside ladders and behind lights, nor how vigorously you'll brush, nor how devoted you will be about maintaining the FC level. Are you one of those fanatics who is willing to stay up all night long and brush and dose every hour when the sun won't be stealing the FC? All these things factor into it.

    Like any home improvement project, it will take longer and cost more than you thought.
    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.
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    Isaac-1's Avatar
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    Re: How much chlorine will I need (gross numbers)

    It is a guess, but I suspect you will need more than 20 gallons, but that is a good start.
    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
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    Re: How much chlorine will I need (gross numbers)

    Welcome to the forum.
    Can you tell if I seem to be on the right track?
    Yes. You have a good idea of the process and it should go well for you. Like Isaac-1, I think 20 gallons is a good start but, like Richard320 says, it is really hard to predict how much it will take.

    Buy plenty, you can always use it later to maintain your FC.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: How much chlorine will I need (gross numbers)

    My CYA is high -- 90, so I'm going to lower it with a partial drain over the weekend. Get the filter backwashed. Be as ready as I can (anything else I should do?)
    Well, you could do a deep cleaning on the sand filter if you haven't done one lately: linky http://www.troublefreepool.com/threa...-a-Sand-Filter

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    Re: How much chlorine will I need (gross numbers)

    +1 to what Casey said about vac to waste since you need to replace water anyway. It's best to get as much solid gunk out of the pool as you can to help the SLAM along. No sense in having that chlorine trying to kill something you can scoop out yourself.
    18' x 48" (42" water depth) Intex Metal Frame 6,700 Gallons
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    Re: How much chlorine will I need (gross numbers)

    Quote Originally Posted by Casey View Post
    SInce you're doing a drain refill, I'd vac the bottom of the pool to waste to get any sludge out that may be lurking down there.
    Now that I know what that is ( ), my old sand filter does not have the plumbing to support it. I do have a separate return for my pool vac with a leaf cannister -- so, I think that's the best I can do.

    Quote Originally Posted by Butterfly View Post
    Well, you could do a deep cleaning on the sand filter
    I had a company out last Monday to try to do a sand change. Unfortunately, my really old filter has bolts all the way around and they couldn't get a couple of them out. They were able to put it back together with no leaks. So, the only option I have will be to get a new filter. Do I have a chance at success without doing anything other than backwashing? Or, should I just get a new filter before I start the process?

    Thanks!
    25K gal, fiberglass, Hayward 1hp pump, Sta-rite 30" sand filter, Hayward Pool Vac

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    Casey's Avatar
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    Re: How much chlorine will I need (gross numbers)

    How old is really old?
    I'd bet you my bikini you'll never get TFP water from a pool store!

    24' Sharkline Venture De Filter

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    Re: How much chlorine will I need (gross numbers)

    I think you will need much closer to 40 gallons than 20. I just turned my swamp to an oasis over one weekend and it took about 35 bottles of 121 oz 8.25% bleach. But I have a great DE filter, my CYA was lower than yours (I had to shock at 28 FC) and my wife and I stayed up testing and cleaning for nearly 48 hours straight with just about 6 hours sleep. But we got it done in a weekend and hopefully you can too! Best of luck.
    John Downing
    El Paso, TX

    16,500 IG, Plaster, DE filter, Pentair FNS Plus 48, 1 HP WhisperFlow NOT variable speed, 5+ years ago.

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    Re: How much chlorine will I need (gross numbers)

    Quote Originally Posted by Casey View Post
    How old is really old?
    The filter and pump were replaced in May 2003. I doubt that I've done anything other than backwashing since then...
    25K gal, fiberglass, Hayward 1hp pump, Sta-rite 30" sand filter, Hayward Pool Vac

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    Re: How much chlorine will I need (gross numbers)

    Sand generally never needs replacing, although deep cleaning the sand may be called for
    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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    Re: How much chlorine will I need (gross numbers)

    UPS should deliver my FAS-DPD chlorine test from TFPTests.com in a few hours.

    Thought I'd post past pictures and then progress.

    Here's the pool a few weeks ago after doing what the pool store said for a week:

    pool140426.jpg

    I spent the next couple weeks just trying to keep the FC level non-zero.

    Last week, after deciding to do TFP and ordering my test kit, I dumped 8 gallons of liquid chlorine in last Tuesday/Wednesday. Chlorine level has actually stayed above 5 while I wait...

    Here it is today:

    pool140519.jpg

    I'll update numbers when I start the SLAM later today. Thank you so much for the support!!
    25K gal, fiberglass, Hayward 1hp pump, Sta-rite 30" sand filter, Hayward Pool Vac

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    Richard320's Avatar
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    Re: How much chlorine will I need (gross numbers)

    That pool will look awesome when it's clear!
    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!

  15. Back To Top    #15

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    Re: How much chlorine will I need (gross numbers)

    With my new chlorine test and after a partial drain/refill over the weekend, here are my numbers:

    FC 1.5
    CC 1.0
    PH 7.2
    TA 120
    CH 425
    CYA 60

    Time to SLAM!

    I'm keeping track of my numbers / additions here : https://docs.google.com/spreadsheets...it?usp=sharing
    25K gal, fiberglass, Hayward 1hp pump, Sta-rite 30" sand filter, Hayward Pool Vac

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    Re: How much chlorine will I need (gross numbers)

    I stayed home (telecommute) today so that I could monitor/maintain the chlorine in the pool.

    I don't see any visual progress, but I've added about another gallon of chlorine today to keep it at shock level and I've had to backwash 3 times.

    A couple questions that I wasn't able to find answers to searching the forums :

    1) What amount of chlorine ppm in the pool would be considered a "slight" drop to indicate I can move to twice daily testing? (My boss is great - I can probably get away with another telecommute day if needed) Biggest drop today was to 20.5 from my shock level of 24 over about 90 minutes.

    2) Is the fact that I needed to backwash 3 times today (due to the pressure rising) a good indication that my filter is doing its job?

    Thanks!

    Toni
    25K gal, fiberglass, Hayward 1hp pump, Sta-rite 30" sand filter, Hayward Pool Vac

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    Smykowski's Avatar
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    Re: How much chlorine will I need (gross numbers)

    Quote Originally Posted by tibunekubda View Post
    1) What amount of chlorine ppm in the pool would be considered a "slight" drop to indicate I can move to twice daily testing? (My boss is great - I can probably get away with another telecommute day if needed) Biggest drop today was to 20.5 from my shock level of 24 over about 90 minutes.

    2) Is the fact that I needed to backwash 3 times today (due to the pressure rising) a good indication that my filter is doing its job?
    1. That's a tough one. Losing 4 ppm in 90 min is a lot. However, we all understand that we have other responsibilities, like work and family and life, that get in the way of playing with the pool (leave Daddy alone, he's testing the pool!!! - overheard in our house). If you have the flexibility of giving it one more day of testing and dosing every hour or two, that would probably set you up for test and dose in the morning, then test and dose as much as you can in the evening. Hit it hard again on the weekend, and you'll be in much better shape for two a day testing.

    2. Yes. And as you progress through the process, the "clean the filter" rate will drop.
    33' round, 23,000 gal AG vinyl , 1HP 2spd PowerFlo Matrix downsized with 3/4HP impeller (X2), Hayward S180T 150# sand filter (X2), Hayward H250 NG heater Pool Store year 1 - $850 for 2 months; Pool Store year 2 - $440 for 2 months, TFPC year 1 - $170 for 4 months; TFPC year 2 - $95 for 4.5 months
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  18. Back To Top    #18

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    Re: How much chlorine will I need (gross numbers)

    Another day done. I still don't see a difference between how it looked on Monday and how it looks today. Still green. I added over 3 more gallons of chlorine over the course of the day today. Only had to backwash the filter once. The pool vac isn't finding as much stuff down deep where I can't see anything.

    I know I'm not patient -- I guess I just expected it to be less green each day.

    Does this still all seem normal? Or, is it time to start wondering about some other problem with the pool/equipment?

    pool140521.jpg
    25K gal, fiberglass, Hayward 1hp pump, Sta-rite 30" sand filter, Hayward Pool Vac

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    Mod Squad tim5055's Avatar
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    Re: How much chlorine will I need (gross numbers)

    What is your FC? How often are you testing and adjusting?

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    Re: How much chlorine will I need (gross numbers)

    Hi -

    Last night at 9:15 my FC was 25. This morning at 6:00 it was at 22. I added 2 quarts of chlorine.

    If it helps, I have all my data in a shared spreadsheet on google drive here : https://docs.google.com/spreadsheets...it?usp=sharing

    The chlorine is clearly getting used up. Since the pool vac stopped picking up much, I've switched the valve over to full skimmer.

    The pool store/service guy recommended a new filter. I wonder if I need that or patience...

    Thanks!

    Toni
    25K gal, fiberglass, Hayward 1hp pump, Sta-rite 30" sand filter, Hayward Pool Vac

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