Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 12 of 12

Thread: Replaced half the water in my pool... What now?

  1. Back To Top    #1

    Join Date
    Jun 2010
    Location
    Arlington, TX
    Posts
    51

    Replaced half the water in my pool... What now?

    When I drained the pool down, the water seemed much cloudier, cloudier than I think can be attributed to removal of the water... I left the filter running through most of the drain/refill (diverter valve set to DRAIN only - no SKIM). Right after refilling, when I brushed the walls/floor, white 'dusty' clouds appeared... never seen this before. Maybe b/c my pool water is normally polished by the DE filter, and this water straight from the city is not as clean? Anyway, after running the filter for another 3 hours this morning, the cloudiness while brushing is practically gone. The overall water clarity is slightly worse than before, but I expect the filter to catch up by the end of the day.

    Here are the test results after the refill, hot off the press:

    FC 1
    CC 0
    pH 7.8
    TA 110
    CH 220
    CYA 50

    So, my question is what should I bring the FC up to? Pool Calculator says that I can add 280 oz. of 6% bleach to bring my FC up to 6 (target according to the TFP Chlorine/CYA Chart). Any need to bring it higher than that as there was some algae present prior to the refill? I've it off the walls, maybe the minor cloudiness is from algae?

    I think I might add some muriatic acid as well to get the pH to 7.5 or so.

    Please advise on what I should do, and how to do it.

    Probably not helpful, but here are the test results from my tap water:

    FC 0.5
    CC 3.5
    pH 8.0
    TA 110
    CH 120
    CYA 0 (waste of regents, wasn't thinking at least my gf got to see how it works! )

    By the way, this is kind of a continuation from another post, found URL here. I figured I might as well have a fresh new thread for a fresh new start!

    Thanks,
    Robert
    27,000 Plaster IG Pool
    DE Filter, 48 sq ft
    Pentair WhisperFlo two speed 1 HP Pump

  2. Back To Top    #2
    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    Location
    SouthWest Alabama
    Posts
    22,347

    Re: Replaced half the water in my pool... What now?

    I don't think you need to shock but you do need to bring your FC up.

    Bringing the pH down is a good ideea too.
    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

  3. Back To Top    #3

    In the Industry

    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    30,083

    Re: Replaced half the water in my pool... What now?

    Even with just that little bit of residual cloudiness, I think I would go ahead and shock it just to be safe. Bama is probably correct that you do not need to but Shocking will get you off to a flying start. (BTW, nice work on getting your CYA down.)

    Lower your pH first, then I would suggest shocking the pool exactly as prescribed in Pool School.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  4. Back To Top    #4

    Join Date
    Jun 2010
    Location
    Arlington, TX
    Posts
    51

    Re: Replaced half the water in my pool... What now?

    I went ahead and added 2 1.42 gallon jugs (364 oz) of 6% bleach. Pool Calc says that should get me to an FC of about 7. How long should I wait before testing it again? I know I read on here somewhere, but can't find it now! What difference does the order in which one adjusts pH and chlorine make?

    Thanks again to everyone here at TFP. Everyone has bee very helpful!



    Robert
    27,000 Plaster IG Pool
    DE Filter, 48 sq ft
    Pentair WhisperFlo two speed 1 HP Pump

  5. Back To Top    #5

    In the Industry

    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    30,083

    Re: Replaced half the water in my pool... What now?

    Lower you pH first. Higher than 10 FC levels makes the pH test invalid.

    7ppm is not bad for FC but 15ppm held there until that cloudiness is completely gone is better!
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  6. Back To Top    #6

    Join Date
    Jun 2010
    Location
    Arlington, TX
    Posts
    51

    Re: Replaced half the water in my pool... What now?

    This morning at 8:00 AM my FC was at 6 (target for CYA 50).

    At 7:00 PM it had dropped to FC 3 (minimum is 4 for CYA 50) with only a small trace of CC (very light pink disappeared with one drop of R-0871). It was very sunny and hot today (100 F high) but the water still looks great.

    Does this drop of FC by 3 ppm seem reasonable? The minimum is 4, so should I target a higher FC for now?

    I went ahead and targeted an FC of 7 for now (added 224 oz of 6% bleach, per pool calc).

    pH 7.5
    TA 110
    CH 220
    CYA 50

    Robert
    27,000 Plaster IG Pool
    DE Filter, 48 sq ft
    Pentair WhisperFlo two speed 1 HP Pump

  7. Back To Top    #7

    Join Date
    Apr 2009
    Location
    Northeast Ohio
    Posts
    221

    Re: Replaced half the water in my pool... What now?

    A 3ppm loss on a sunny day is pretty normal. If you're not going to shock, I'd target a little higher nightly FC (8 or 9), so that by the next evening it's still above 4. You never want it to go below 4 even for a little while, adjusting your nightly dose should help with that.
    32x16 ft Grecian rectangular vinyl pool 8ft on deep end - 19000 gal. 18" Hayward S-240 sand filter. 250K BTU Pentair MasterTemp heater. Hayward 3/4 HP Super Pump.

  8. Back To Top    #8

    Join Date
    Jun 2010
    Location
    Arlington, TX
    Posts
    51

    Re: Replaced half the water in my pool... What now?

    Definitely no need to shock... I think I was just taking the Chlorine / CYA Chart a little to literally :P It suggests a Target of 6, but maybe correcting to 8 or 9 seems reasonable in anticipation of many hot sunny days to come. If I target 8..9, that should keep me away from my minimum of 4 .

    Any thoughts?

    BTW when I add the chlorine, I pour it slowly in front a return jet at the deep end, and then leave the pump on for about 30 minutes, is that adequate?

    Thanks,
    Robert
    27,000 Plaster IG Pool
    DE Filter, 48 sq ft
    Pentair WhisperFlo two speed 1 HP Pump

  9. Back To Top    #9

    Join Date
    Apr 2009
    Location
    Northeast Ohio
    Posts
    221

    Re: Replaced half the water in my pool... What now?

    Sounds good with the exception that I'd probably run the pump for at least an hour. I tried searching other posts to see what others recommend, but didn't come up with anything concrete enough to point to other than some suggestions for running one to three hours after adding chemicals in the evening.

    My two cents is, run it for at least an hour if you can. See where 7 ppm from tonight leaves you tomorrow evening, if it's not above 4, go to 8 or 9 until you find what works for you.
    32x16 ft Grecian rectangular vinyl pool 8ft on deep end - 19000 gal. 18" Hayward S-240 sand filter. 250K BTU Pentair MasterTemp heater. Hayward 3/4 HP Super Pump.

  10. Back To Top    #10

    Join Date
    Jun 2010
    Location
    Arlington, TX
    Posts
    51

    Re: Replaced half the water in my pool... What now?

    That sounds very reasonable.

    Right now my pump timer is set from 6 am to 6 pm, but now that I will be adding the bleach around 7pm to 9pm every night, I'm thinking of changing it to something like 10am to 10pm...

    Robert
    27,000 Plaster IG Pool
    DE Filter, 48 sq ft
    Pentair WhisperFlo two speed 1 HP Pump

  11. Back To Top    #11
    Butterfly's Avatar
    Join Date
    May 2007
    Location
    South Carolina
    Posts
    10,045

    Re: Replaced half the water in my pool... What now?

    As loughps said, running the pump at least an hour after adding chems is a good idea, in fact it is recommended.

    Lots of us jug dumpers add our nightly dose and then turn the pump off after an hour.

    Sometimes I will shorten the one hour run time after dosing if I am in a particular hurry; but, I will help mix the chlorine/bleach by using a brush or water hose to help stir the water and mix.
    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.

    ~ One should not use a sledge hammer to swat a mosquito. ~

    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  12. Back To Top    #12

    Join Date
    Jun 2010
    Location
    Arlington, TX
    Posts
    51

    Re: Replaced half the water in my pool... What now?

    Thanks for the tips.

    For anyone else asking the same newbie questions as me, I found some helpful advice from the Pool Calculator Basic Chemistry page

    The target FC level is a minimum. You always want the FC level to be at least as high as the target level. FC is commonly lowest in the evening after sunlight has been reducing it all day. If you are adding chlorine once a day in the evening you need to bring the chlorine up to a higher number than this so that your FC level the next evening is at least the target level. How much higher depends on your CYA level, the amount of sunlight that falls on the pool, and how much the pool is used. A CYA of 30 to 50 will generally lose between one half and two thirds of the FC over the course of a sunny day.
    Based on that, I will add enough bleach to bring my FC level up to Target + 'anticipated chlorine loss over the next 24 hours'. For me this will be 6 + 3 = 9.

    That way my chlorine level should cycle between 6 and 9 every day.

    Robert
    27,000 Plaster IG Pool
    DE Filter, 48 sq ft
    Pentair WhisperFlo two speed 1 HP Pump

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •