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Thread: Algae; not sure what to do

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    Algae; not sure what to do

    7.5 FC (just added 96oz. to bring it to 10.5)
    7.5 pH
    100 TA
    CYA ?

    My pool has has had light green film on bottom for about two weeks. I think I let the FC go below 3 ppm for a couple of days and did not vacuum for 2 weeks. I brought the FC up to 10 as soon as I saw a light green area (two weeks ago) and ran my kreepy krawly. The water became cloudy. pH was at 8.0 to 8.2, I bought ph down from box store to get that back in order. I began running the vacuum 3 to 5 hours a day every day since last Thursday (6 hours on Saturday and Sunday). Raised FC to 10ppm on Friday and kept it there Saturday, it fell to 9.5 Saturday evening so I added the recommended amount on the pool calculator to bring it back to 10 ppm. I ran pump non-stop from Friday night to Sunday night. This afternoon (Monday) it was at 7.5 and a lot of green on the bottom. Kreepy Krawly began sticking to bottom today, I have never seen that, but it tends to miss some spots. It seems to be getting worse, not better. I'm at a loss as to what to do. Pool has been crystal clear since June by keeping ph, TA, FC and CYA at recommended levels. I'm thinking I need to get in daily and scrub bottom and sides.
    A green cloud comes out of the return when pump is turned on. We have had a good amount of rain here in North Texas for a couple of weeks now. Does that contribute to the algae?

    Any advice is much appreciated.
    15,200 gallon 24' X 52" round AG; installed 2011; SWG
    1 ½ hp Dynamo pump; Pentair Meteor sand filter, 2.1 sq. ft. filtration area, 42 GPM flow rate
    TF 100 Test Kit

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    linen's Avatar
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    Re: Algae; not sure what to do

    We/you need to know the cya level to move forward with the shocking process that your pool needs.
    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.

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    Re: Algae; not sure what to do

    Thanks linen.
    I'll check it in the morning. Water is relatively clear then.
    15,200 gallon 24' X 52" round AG; installed 2011; SWG
    1 ½ hp Dynamo pump; Pentair Meteor sand filter, 2.1 sq. ft. filtration area, 42 GPM flow rate
    TF 100 Test Kit

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    Re: Algae; not sure what to do

    the reason it is getting worse not better is most likely because your not at shock level per your cya level thus letting the algae grow, please post up a full set of test results so we can help you get your pool sparkly clear again, also the ph test will show falsly high for fc >10 ppm i would let fc drop below 10 ppm so you can get a accurate reading on ph and lower it to around 7.2 prior to starting the shocking process...jmo.....Mike
    18x52 intex ultra frame pool 6981 gallons, 1 HP LL pump with 19 in sand filter,BBB method,borax 50ppm
    leslies DPD test kit + fas-dpd chlorine test kit + borates test strips
    thru wall skimmer,hard plumbed with 2 returns 1 1/2 sch 40 pvc
    1 large fountain 1 inch sch 40 pvc,shut off ball valves on all

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    Re: Algae; not sure what to do

    Updated test results: 12:15pm Tuesday

    FC 8
    CC > .5
    pH 7.6
    TA 100
    CYA 40

    CYA test - as I slowly add drops per instructions, the dot at the bottom is gone briefly at 60. Less than 1 second later it is visible. It disappears and stays gone at 40. Am I reading this correctly at 40?
    15,200 gallon 24' X 52" round AG; installed 2011; SWG
    1 ½ hp Dynamo pump; Pentair Meteor sand filter, 2.1 sq. ft. filtration area, 42 GPM flow rate
    TF 100 Test Kit

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    Mod Squad Bama Rambler's Avatar
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    Re: Algae; not sure what to do

    I would say it's probably close to 50. But anywhere between 40 & 50 is fine to use.
    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
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    Re: Algae; not sure what to do

    JasonLion posted that a pool should be at 7.2 to 7.4 pH before beginning the shock process. At 8 ppm FC can I trust my reading of 7.6 pH and begin to bring it down or should I let the FC drop more and take another pH reading?
    With a CYA value of 50, the pool calculator says my shock level is 16ppm. A value of 60 the shock level is 18ppm. Is it ok to go high?
    How long do I keep the pool at shock level?
    15,200 gallon 24' X 52" round AG; installed 2011; SWG
    1 ½ hp Dynamo pump; Pentair Meteor sand filter, 2.1 sq. ft. filtration area, 42 GPM flow rate
    TF 100 Test Kit

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    Mod Squad jblizzle's Avatar
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    Re: Algae; not sure what to do

    pH test is affected once the FC > 10ppm. Lower you pH a bit before starting the shock process.
    From the more aggressive Chlorine CYA Chart, shock level is 20ppm for a 50ppm CYA. You will not damage anything if you stay below the mustard shock level listed in the calculator (if that is what you are worried about). Just pick something between 16ppm and 20ppm as your target.

    You stay at shock level until you pass the 3 test to stop: Shocking Your Pool
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Re: Algae; not sure what to do

    Quote Originally Posted by Toomchfun
    JasonLion posted that a pool should be at 7.2 to 7.4 pH before beginning the shock process. At 8 ppm FC can I trust my reading of 7.6 pH and begin to bring it down or should I let the FC drop more and take another pH reading?
    The pH test is accurate with the FC below 10. So, yes, trust your test.

    With a CYA value of 50, the pool calculator says my shock level is 16ppm. A value of 60 the shock level is 18ppm. Is it ok to go high?
    Shock level for CYA of 50 is betweel 16 (Pool Calculator) and 20 (CYA/Chlorine Chart).

    How long do I keep the pool at shock level?
    Maintain the shock process until you meet the three criteria that show you are done. See red lines in my sig.
    ETA:Jason is fast.
    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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    Re: Algae; not sure what to do

    How long do I keep the pool at shock level?
    That is the answer that eludes many, many newbies and that answer is the key to shocking correctly.

    Read the article in Pool School on How to shock your pool and you will find you need to keep the FC high much longer than you think.

    YOur pH result of 7.6 is close enough....I would shock without lowering the pH. It is also a valid reading you can trust.

    Don't get your FC too high. That's why there are guidelines. 16ppm is fine but do not assume you can put in an unlimited amount of FC. Use 16 as your target if you like but retest often so you can replenish FC back to 16.

    (Jason and Butterfly are BOTH fast)
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: Algae; not sure what to do

    Thanks for all the feed back! A few more questions before I begin.

    My AGP has no deck. How do folks brush while at shock level without getting in? Is it safe to enter?
    How many minutes do I backflush and rinse my sand filter and how often during this process? Usually I go until the water is clear, is that the same for the shock process?
    Should I run my Kreepy Krawly vacuum during this process?
    15,200 gallon 24' X 52" round AG; installed 2011; SWG
    1 ½ hp Dynamo pump; Pentair Meteor sand filter, 2.1 sq. ft. filtration area, 42 GPM flow rate
    TF 100 Test Kit

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    Re: Algae; not sure what to do

    Brush as well as you can ... actually getting in is not really a problem ... since you will not be putting your face in the water. We do not typically recommend getting in the water when FC is greater that shock level and you can not see the bottom (if you slipped under the water ... no one would be able to see you).

    You should backwash when the filter pressure goes up 20-25% of your clean pressure. Then backwash until the water is clear. Do you have a multi-valve? If so some people alternate between backwash and rinse a few times.

    There should not be a problem with running the vacuum during the shock process.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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    Re: Algae; not sure what to do

    I'm not sure what a multi-valve is. The top of the filter has the options with a notch at each one. I turn the pump off, push down on the lever and turn to the desired option, then turn the pump back on.
    15,200 gallon 24' X 52" round AG; installed 2011; SWG
    1 ½ hp Dynamo pump; Pentair Meteor sand filter, 2.1 sq. ft. filtration area, 42 GPM flow rate
    TF 100 Test Kit

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    Mod Squad jblizzle's Avatar
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    Re: Algae; not sure what to do

    That is a multi-valve. Some filters only have a push/pull valve with only the backwash option.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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    Re: Algae; not sure what to do

    This is my valve[attachment=0:3fylp8fn]untitled.bmp[/attachment:3fylp8fn]
    15,200 gallon 24' X 52" round AG; installed 2011; SWG
    1 ½ hp Dynamo pump; Pentair Meteor sand filter, 2.1 sq. ft. filtration area, 42 GPM flow rate
    TF 100 Test Kit

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    Mod Squad jblizzle's Avatar
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    Re: Algae; not sure what to do

    If it has a rinse/clean option, then alternating between it and backwash a couple times will clean things out a little better.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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    Re: Algae; not sure what to do

    May I please ask a related question here? Does it mean it is not safe to put your face in the water when FC is greater than shock level? I did that multiple times while shocking my pool.

    I yet to clean my lights. Shall I let FC come down and then do that? Thank you!

    Quote Originally Posted by jblizzle
    Brush as well as you can ... actually getting in is not really a problem ... since you will not be putting your face in the water. We do not typically recommend getting in the water when FC is greater that shock level and you can not see the bottom (if you slipped under the water ... no one would be able to see you).

    You should backwash when the filter pressure goes up 20-25% of your clean pressure. Then backwash until the water is clear. Do you have a multi-valve? If so some people alternate between backwash and rinse a few times.

    There should not be a problem with running the vacuum during the shock process.
    20,000 gallons, IG plaster, probably built in the 80's.
    Filter: Hayward Pro-Grid DE6020, 120 GPM.
    Pump: Magnetek century E-plus, Purex Triton Whisperflow, WFE-4C, 1HP.
    Fountain booster: Century Centurion A O Smith, CAT B848, 1HP.
    Spa booster: G.E. Jacuzzi pump
    Heater: Raypak RP2100 Digital, Low Nox

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    Mod Squad jblizzle's Avatar
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    Re: Algae; not sure what to do

    Quote Originally Posted by xiaobulu
    May I please ask a related question here? Does it mean it is not safe to put your face in the water when FC is greater than shock level? I did that multiple times while shocking my pool.

    I yet to clean my lights. Shall I let FC come down and then do that? Thank you!
    Ugh ... I never should have said anything. It is not so much the high FC that is a problem ... but if you have higher CC since you are in the shock process, they could be more irritating. Or there could be other things in the water that required the shock process.

    Easiest to just say ... safe when FC is below shock level, CC is not more than 0.5ppm, and you can see the bottom ... Because that implies that you have completed the shock process.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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    Re: Algae; not sure what to do

    Alright. Thanks!


    Ugh ... I never should have said anything. It is not so much the high FC that is a problem ... but if you have higher CC since you are in the shock process, they could be more irritating. Or there could be other things in the water that required the shock process.

    Easiest to just say ... safe when FC is below shock level, CC is not more than 0.5ppm, and you can see the bottom ... Because that implies that you have completed the shock process.
    20,000 gallons, IG plaster, probably built in the 80's.
    Filter: Hayward Pro-Grid DE6020, 120 GPM.
    Pump: Magnetek century E-plus, Purex Triton Whisperflow, WFE-4C, 1HP.
    Fountain booster: Century Centurion A O Smith, CAT B848, 1HP.
    Spa booster: G.E. Jacuzzi pump
    Heater: Raypak RP2100 Digital, Low Nox

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    Re: Algae; not sure what to do

    Tuesday evening:
    FC 8 ppm
    Cleaned skimmer basket
    Cleaned lower basket
    Backflush and rinse
    brushed sides and bottom of pool
    Raised FC to 18.5 ppm

    Wednesday 7:00am
    FC 18 ppm
    water cloudy

    Wednesday 12:00 noon
    FC 13 ppm
    Raised FC to 18

    Wednesday 6:00 pm
    FC 13 ppm

    7:00pm
    FC 20.5 ppm
    Water looks better
    Ran vacuum 7:00 pm to 10:15pm

    Pump running non-stop
    15,200 gallon 24' X 52" round AG; installed 2011; SWG
    1 ½ hp Dynamo pump; Pentair Meteor sand filter, 2.1 sq. ft. filtration area, 42 GPM flow rate
    TF 100 Test Kit

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