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Thread: Algae - SLAM (or use Shock?)

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    Algae - SLAM (or use Shock?)

    Hello,

    Thanks again everyone, I came here last fall after moving in, but just after I got the info of what to do with the pool, I got seriously ill and didn't do anything. I wasn't better until February, so now the temps are slowly getting higher and I need to get things in order.

    Two months of neglect put the pool in bad condition. I've been skimming and scooping daily, and had it fairly cleared except there is some sediment on the bottom I can't get out. When the temps got warm and with a few rains, it started to green, and now it's VERY GREEN. It's been that way about a week. I finally figured out that our old liquid chlorine must just be simply dead.

    Test results are this:
    TA - 40
    CYA about 75 or 80 (not good at this yet)
    pH 7.5
    FC 0
    No readable chlorine at all

    Pool is roughly maybe 18K
    vinyl liner and DE filter (that may be wrong in my sig), inground chlorine pool

    I'm reading Pool School and using the calculator and a little confused. I'm guessing I'm supposed to add 341 oz. of 10.5% bleach (I have on hand 640 oz.)

    While I was at the pool store, I was told (and I know I probably shouldn't listen, but it's a good drive, and he sounded convincing) - he said I could use shock powder (73% calcium hypochlorite) and put in a little over a pound (maybe 2), wait a day, put in the same amount again, and it would be done. I probably shouldn't believe it's that simple, but the store is a good drive and it was sounding cheaper and easier, so I bought 2 pounds.

    He said it would be more stable, and that it would diffuse better in the water (which makes no sense to me). Cost was the same though so I thought maybe he was telling me the truth (1 pound shock is same cost as 2.5 gal. bleach) - I didn't know the strength of the shock powder then, but it's 73%

    I had time today, and was hoping to do through the morning, but we are having a terrible rainstorm, and I'm not sure how practical that is. I didn't skim yesterday either, and one day means a lot of leaves here (the live-oaks are losing their leaves in spring).

    So I hate to be starting with such a basic set of questions, what should I do?

    (BTW, my CYA might not be accurate, I followed directions, but I read on another post that murky water may make it higher and I didn't filter it - the water looks only very slightly cloudy in a filled container, but it doesn't look perfectly clean. And my eyes are not great so it was very hard to really see it.)

    Thanks for any help.
    Total pool newbie - maybe 18K gal. inground chlorine pool (oval 33 x 14 - 3 to 8.5' depth), vinyl liner, sand filter - near Pensacola, FL

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    JasonLion's Avatar
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    Re: Algae - SLAM (or use Shock?)

    The pool store approach works some of the time, and fails other times. Our approach works 99+% of the time. SLAMing is a more methodical approach that works because you test levels and adjust to what you need. The pool store approach depends on getting lucky, which happens often enough but is nowhere near dependable.

    Take a look at the Pool School article on how to SLAM your pool and follow the directions there.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Algae - SLAM (or use Shock?)

    The specific reason to stay away from the Cal Hypo is that it adds calcium which will eventually lead to scaling.

    Liquid Chlorine (aka bleach) is the way to go.

    Given 18K gallons and a CYA of 80 (target shock level of 31 per pool math) you need to add 661 OZ of 10.5% liquid CL ... test the CL level every hour and use poolmath to calculate how much CL to add to keep it at 31 until you pass the overnight drop test.

    What test kit do you have?
    TFP Moderator Chris V. ~16K Pool & Spa, 48NSF DE, IG Plaster Circa 2000, Intermatic PE653, Challenger pump with a 2 speed B2984, 20gal stenner chlorine injection, Houston, TX
    One cannot follow Islam and Christianity at the same time, nor can one follow pool store methods and TFP at the same time.
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    Re: Algae - SLAM (or use Shock?)

    Thanks very much. Hopefully then they will let me exchange the shock powder for liquid chlorine. He was recommending so much less, volume-wise. If I compare the two on the pool math calculator, it would take 3x as much shock as chlorine (per the same cost amount). And I was concerned about the actual effect of adding the shock that I might not know about, so thanks for the heads-up.

    I have the TF-100 test kit.

    I think I'm going to have to wait for another day. At 10am it's almost night-time dark out there, and pouring rain. Hopefully I will have another day very soon that I can be available to devote to it.

    Is the pH of 7.5 close enough, given that the CYA may be high, and I may not be reading it correctly?

    Will so much rain have a particular effect? I keep trying to "change out" some water, but as much as I can pump out before it causes a problem on the ground, it keeps filling back up with rain. We had about 12 inches of rain in Jan-Feb, and I think March has been much higher than before (no totals yet). I know I drain a bit out at least 2-3 times a week, and only add while using the leaf rake.

    I'll probably re-do the CYA test, since it makes such a difference, if I understand correctly? Maybe I will see if my daughter or husband can do it, since my eyes are not great.

    Thanks again. Hopefully this weekend. The water temp has come up 10 degrees in the past few weeks and we are anxious to use it if it ever gets warm enough - it took so long to buy the house, we moved in and only got to swim a couple of times before it got too cold.
    Total pool newbie - maybe 18K gal. inground chlorine pool (oval 33 x 14 - 3 to 8.5' depth), vinyl liner, sand filter - near Pensacola, FL

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    Re: Algae - SLAM (or use Shock?)

    If you have an umbrella and there isn't lightning the dark outside can work in your favor as the sun wont be burning any CL off.

    PH is close enough.

    For the purposes of SLAMing the pool the rain affect is negligible. For the purpose of bringing CYA down to a normal level rain is great stuff, it just takes a LOT of rain over a long period.

    I personally like to start my SLAM in the late afternoon to give the FC the best chance to destroy algae without being burned off by sunlight. When a rainy day coincides with me letting the pool get away from me it is a wonderful thing.
    TFP Moderator Chris V. ~16K Pool & Spa, 48NSF DE, IG Plaster Circa 2000, Intermatic PE653, Challenger pump with a 2 speed B2984, 20gal stenner chlorine injection, Houston, TX
    One cannot follow Islam and Christianity at the same time, nor can one follow pool store methods and TFP at the same time.
    Pool School -- Pool Math -- TF-Test Kit

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    Re: Algae - SLAM (or use Shock?)

    Oh, thank you for that. I'll go ahead and do it then. I can at least test and add chlorine.

    I'm not at all sure I can get the leaves skimmed - and there are probably a lot with 2 days plus high winds. On a bad day it covers about 1/3 of the surface in floating mats, and that's with removing all the day before.

    There is some lightning off and on. And no umbrella, but I won't melt. Like I said, I can handle the adding chlorine and testing, but no long metal pole ...

    Thanks again!

    - - - Updated - - -

    Errr .... maybe. I have not looked outside in about an hour and a half, and the pool is JUST ABOUT to overflow. Not sure what to think. I doubt I can drain off much because of all the rain.
    Total pool newbie - maybe 18K gal. inground chlorine pool (oval 33 x 14 - 3 to 8.5' depth), vinyl liner, sand filter - near Pensacola, FL

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    Re: Algae - SLAM (or use Shock?)

    CYA tested again, my husband has better eyes, and filtered pool water first. I think it's closer to 65. So I'm aiming for an FC of 26 I believe. Going to put in the chlorine tonight, and I did manage to skim, clean both baskets (not many leaves actually) and scooped the bottom though I can't see it.
    Total pool newbie - maybe 18K gal. inground chlorine pool (oval 33 x 14 - 3 to 8.5' depth), vinyl liner, sand filter - near Pensacola, FL

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    Re: Algae - SLAM (or use Shock?)

    Going a couple of points worth of FC higher than you think you need is not a bad idea due to the plus or minus 10% accuracy of the cya testing in the first place. Won't hurt a thing!
    16x32x52" Steel Cornelius Miramar AGP Vinyl liner 13,100 gal. Buried 2 ft.
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    Re: Algae - SLAM (or use Shock?)

    Thank you.

    I put in the amount of fresh chlorine needed to bring it to 26, then poured in the rest of the old chlorine (that didn't seem to be working well enough) - about another gallon. So that would put it closer to the higher CYA level, if that chlorine had any strength.

    I drained about 5 or 6" worth of water, and the rain had come in, so I changed a tiny bit.

    I'm just testing chlorine at this point, right? Keeping FC around 26-30?

    I just base everything else off the numbers I got in the test before I started, right?

    Thanks again.
    Total pool newbie - maybe 18K gal. inground chlorine pool (oval 33 x 14 - 3 to 8.5' depth), vinyl liner, sand filter - near Pensacola, FL

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    Re: Algae - SLAM (or use Shock?)

    Correct. Just testing cl and keeping it in that range. Don't be surprised if you have to add a lot the first few hours.
    TFP Moderator Chris V. ~16K Pool & Spa, 48NSF DE, IG Plaster Circa 2000, Intermatic PE653, Challenger pump with a 2 speed B2984, 20gal stenner chlorine injection, Houston, TX
    One cannot follow Islam and Christianity at the same time, nor can one follow pool store methods and TFP at the same time.
    Pool School -- Pool Math -- TF-Test Kit

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    Re: Algae - SLAM (or use Shock?)

    Jason- we must have been pounding out our responses simultaneously.
    TFP Moderator Chris V. ~16K Pool & Spa, 48NSF DE, IG Plaster Circa 2000, Intermatic PE653, Challenger pump with a 2 speed B2984, 20gal stenner chlorine injection, Houston, TX
    One cannot follow Islam and Christianity at the same time, nor can one follow pool store methods and TFP at the same time.
    Pool School -- Pool Math -- TF-Test Kit

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    Re: Algae - SLAM (or use Shock?)

    Trishanna - how's it looking? How much CL are you loosing between tests?
    TFP Moderator Chris V. ~16K Pool & Spa, 48NSF DE, IG Plaster Circa 2000, Intermatic PE653, Challenger pump with a 2 speed B2984, 20gal stenner chlorine injection, Houston, TX
    One cannot follow Islam and Christianity at the same time, nor can one follow pool store methods and TFP at the same time.
    Pool School -- Pool Math -- TF-Test Kit

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    Re: Algae - SLAM (or use Shock?)

    Thanks for checking on me and clarifying.

    I have a question though.

    Do I keep adding drops of the R-0871 until it no longer turns back to pink after a few seconds? Or do I stop as soon as it first turns clear?

    If the former, I don't know really how much chlorine I have (8 or higher), because it keeps turning back to pink. If the latter, I've gone down to 1.5 FC overnight, when I added enough chlorine to bring it up to 26 (and then some - maybe 30? depending on how effective the old chlorine I dumped the rest of would be).

    Please let me know, I really don't know where I stand now?

    - - - Updated - - -

    (I know I may be "starting over" since I did it at night and didn't test until the morning, and now I'm not sure whether I'm doing it right.)

    BTW, the backwash produced a lot of nasty water and took about 2-3 times as long to run close to clear as normal, and never looked as clean. And I can see the bottom of the pool in the shallow end (and the leaves there!) when I couldn't see it at all yesterday or the day before.

    So slight improvement, I would say, visually. My husband says the green is better, and less dark-ish (it has been near black-ish in the deep end)
    Total pool newbie - maybe 18K gal. inground chlorine pool (oval 33 x 14 - 3 to 8.5' depth), vinyl liner, sand filter - near Pensacola, FL

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    Smykowski's Avatar
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    Re: Algae - SLAM (or use Shock?)

    The first time it goes to clear, stop. That's your reading.

    It's normal for the solution to turn pink again if you leave it sitting for a few minutes. Ignore that part.
    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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    Re: Algae - SLAM (or use Shock?)

    Ugh, well thank you.

    That means my FC is 1.5. So yeah, starting (almost) from scratch.

    Off to the pool store again. I wonder if they are open tomorrow. I need to check before I start, as I only have containers for 7.5 gal.

    Thanks very much for the answer.
    Total pool newbie - maybe 18K gal. inground chlorine pool (oval 33 x 14 - 3 to 8.5' depth), vinyl liner, sand filter - near Pensacola, FL

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    Re: Algae - SLAM (or use Shock?)

    I know it seems like the end is far away, but you'll get there.

    Dark green means a lot of bleach will be needed, so prepare yourself for that (but it's still going to be cheaper in the long run to do it right and definitely cheaper than going to the pool store).

    The more often you can test and redose, the better. If you have the time to devote, every 60-90min would be best. You can space it out as the FC starts to hold longer and longer.
    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
    The most important article on this site - The ABCs of Pool Water Chemistry

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    Re: Algae - SLAM (or use Shock?)

    Worst case hit Home Depot or lowes. Most will have 10.5% and almost all will have household 8.25%. You aren't really starting over ... You just aren't staying ahead of it. Don't sweat it you will get there. Hit it every hour when you can, test and dose. If you don't think it is getting there overshoot the cl level rather than undershoot. If you are going to be away for a long period overshoot further. Once you start getting visible changes it moves quickly.

    Good job!


    TFP Moderator Chris V. ~16K Pool & Spa, 48NSF DE, IG Plaster Circa 2000, Intermatic PE653, Challenger pump with a 2 speed B2984, 20gal stenner chlorine injection, Houston, TX
    One cannot follow Islam and Christianity at the same time, nor can one follow pool store methods and TFP at the same time.
    Pool School -- Pool Math -- TF-Test Kit

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    Re: Algae - SLAM (or use Shock?)

    Thanks so much - I feel better.

    Quick question? I've read some here, enough to know not to trust pool store testing. I thought since it's free I'll compare.

    Results TA 55
    pH 7.8
    Cya 136 (she said it's probably not accurate due to chlorine)
    Calcium hardness 35
    Free chlorine / total chlorine 43+

    The chlorine part REALLY threw me off. I asked for an explanation - I think she only did one test (turn the water pink) and she said the numbers "work together" and they are the same reading.

    Do I just ignore that and go with FC 1.5 I got? I didn't even retest the little pH/chlorine tube where you add drops to both sides. Should I? I get the impression that's what she did to get the 43?

    Thanks much.
    Total pool newbie - maybe 18K gal. inground chlorine pool (oval 33 x 14 - 3 to 8.5' depth), vinyl liner, sand filter - near Pensacola, FL

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    Smykowski's Avatar
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    Re: Algae - SLAM (or use Shock?)

    Do yourself a favor and don't bring a sample to the pool store again. You have a TF-100, so your equipment is better than theirs.

    Those test results don't make any sense.
    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
    The most important article on this site - The ABCs of Pool Water Chemistry

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    Re: Algae - SLAM (or use Shock?)

    Bad data is worse than no data. Pool store is almost always wrong. Stick with your results.


    TFP Moderator Chris V. ~16K Pool & Spa, 48NSF DE, IG Plaster Circa 2000, Intermatic PE653, Challenger pump with a 2 speed B2984, 20gal stenner chlorine injection, Houston, TX
    One cannot follow Islam and Christianity at the same time, nor can one follow pool store methods and TFP at the same time.
    Pool School -- Pool Math -- TF-Test Kit

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