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Thread: clear to green in under 2 days...why?

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    clear to green in under 2 days...why?

    I opened my pool a few weeks ago and things have been going along good. I've been running the filter on and off (mostly on because I forget to shut it off for days at a time) and testing to make sure things are relatively normal, even though there wasn't any swimming--the water was still only around 60F. the water was totally clear and clean from opening.

    fast forward to 3 days ago...beautiful weather predicted--heat wave to the 90's so I take the leaf net off and throw the solar cover on. the kids are drooling at the idea of swimming already--so I pull the solar cover off today to do another vacuuming before the weekend and UGGHHHH....it's a horrible green. I don't see any algae, of course I can't see the bottom...heck I can't even see my hand a few inches down I bet.

    what is the problem and how do I fix it--we've had a ton of pollen floating around here this year--could that be it? if it's algae why can't I see it built up and how did it take hold so fast in the entire pool?

    test results...
    fc 6.5
    cc 0
    tc 6.5
    ph 7.2
    ta 50
    cya 15

    oh..I have about a lb of stabalizer disolving in a sock in the pool right now to raise the cya
    27' round AGP, 2hp 2speed pump & 150sf cartridge filter --taking a stab at BBB and eyeing all the cool gadgets available for pools ;)

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    Someone smarter than me will be along soon, but I'm wondering if it could be copper.
    17K gallon in-gound pool, black plaster, Polaris 380, cartridge filter system

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    duraleigh's Avatar
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    The chances that it is anything other than algae are remote. It got there by allowing the FC levels to get too low over a period of time where the algae coulod take hold. It had probably already started when you put the cover on but I don't know that.

    The cure for algae is chlorine......lot's of it. I can't tell you exactly how much because you are increasing your CYA to a level that I don't know. Post up the CYA target number you have calculated and we'll get you started shocking the pool.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Was the FC of 6.5 and the CYA of 15 (the latter I presume you are estimating since the kit will only read as low as 20 or 30 depending on the kit) something you measured with your own test kit after removing the cover? So was the FC at least that high when you put the cover on before the two days?

    Usually, algae will turn the water dull and then cloudy before full green and usually that takes around 3 days, but under more ideal conditions it could take a couple of days. However, if there was chlorine in the water and not much CYA then something about this situation doesn't make sense.

    You can always do a bucket test with your pool water to see if adding chlorine makes the green turn gray in which case it's algae.

    Richard
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Quote Originally Posted by duraleigh
    The chances that it is anything other than algae are remote. It got there by allowing the FC levels to get too low over a period of time where the algae coulod take hold. It had probably already started when you put the cover on but I don't know that.

    The cure for algae is chlorine......lot's of it. I can't tell you exactly how much because you are increasing your CYA to a level that I don't know. Post up the CYA target number you have calculated and we'll get you started shocking the pool.
    I understand that algae is a result of too little chlorine...but 6.5 is higher than I had it most of last season without problems. why would this develop now without 1) a swim load or 2) warm weather? so far we've only had a couple days make it to 70f, and many nights drop down to the 40's and 50's...even some 30's. the only reason I opened the pool this early is because I used a mesh winter cover so I wanted to get the water circulating to prevent any issues.

    my FC has been over 5ppm since opening, I think it's held pretty steady due to the lack of heat though I could be wrong. I have about 1 lb of stabilizer disolving in the pool now, I think that should raise my cya to around 25 or so, if I'm figuring right.

    I've since added 4.5g of bleach--so that should raise my fc to around 25ppm...too dark to tell if it will make a difference til morning.
    27' round AGP, 2hp 2speed pump & 150sf cartridge filter --taking a stab at BBB and eyeing all the cool gadgets available for pools ;)

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    Quote Originally Posted by chem geek
    Was the FC of 6.5 and the CYA of 15 (the latter I presume you are estimating since the kit will only read as low as 20 or 30 depending on the kit) something you measured with your own test kit after removing the cover? So was the FC at least that high when you put the cover on before the two days?

    Usually, algae will turn the water dull and then cloudy before full green and usually that takes around 3 days, but under more ideal conditions it could take a couple of days. However, if there was chlorine in the water and not much CYA then something about this situation doesn't make sense.

    You can always do a bucket test with your pool water to see if adding chlorine makes the green turn gray in which case it's algae.

    Richard
    yes, the fc was the same before I put the solar cover on, not sure about the cya because I didn't test it then--but I assume so. it's down a bit from last year because of the partial drain and then refill from the winter closing. I used the TF test kit..I did estimate the 15, it was a bit higher than the 20ppm line. there was no dullness or cloudy water as recently as yesterday--when the kids were out there pulling the cover back to check out the water and swear to me that it wasn't too cold to go for a swim. the highest temp we've seen so far this year was 76...and that was for one day only--mainly we've been in the high 50 to low 60..and some pretty chilly nights...that doesn't seem like ideal conditions to me for algae, that's why I'm so baffled.

    I dealt with a bit of algae last season--cleared it up without a problem, this confuses me because I don't see the teltale signs of algae...none growing around the skimmer or on the side wall at waterline...no slick feeling to the water---just a weird green shade to the water. I've dumped a buttloade of bleach in and I guess I just have to wait and see tomorrow morning if it looks any better at all I was sooo proud, the pool was beautiful up until this--from the moment it opened, many neighbors were jealous and were considering converting to BBB--I have to make sure they don't get a look at the leprechaun pee that is my poool water right now
    27' round AGP, 2hp 2speed pump & 150sf cartridge filter --taking a stab at BBB and eyeing all the cool gadgets available for pools ;)

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    mbar's Avatar
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    Could there have been some algae on the solar cover? Sometimes if the chlorine is just a tad low, and some algae is introduced, then the algae starts to eat the chlorine, and bingo an algae break that you never saw coming Just a thought on what might have happened
    16x33 fiberglass pool sand filter

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    I have decided that as soon as chem geek, waterbear, duraleigh or anyone out there figures out how to test for Algae- they will be millionaires.

    I have to agree it is algae. I have never seen algae, and yet it seems to bloom quickly and aggressively. Last year we filled the chlorinator and left a beautiful sparkly pool to go on vacation. Came back and it was swamp green - within a week. This year I am having someone put in bleach everyday!!!
    16 X 34 21,000 IG Vinyl Liner
    1 1/2 Hayward SuperPump
    New Sand Filter (had cartridge - hated them)

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