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Thread: Algae is always coming back

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    Algae is always coming back

    Hi everyone,

    Current readings are:

    FC - 12.5ppm
    CYA - 65
    PH - 7.8

    I know the PH is high and I need to bring it down. The FC is that high because I'm just trying to see if I can burn out some of the Algae.

    Basically, I had an algae problem a couple weeks ago and I used the SLAM protocol and got crystal clear after a week of high FC, brushing the pool, and cleaning the filter daily. As soon as it was clear I was keeping the FC around 5-7ppm as a constant. I believe one day it dipped down to 3ppm but that was only for a day.

    The family has been using the pool and all of the sudden in the last week it started to get a little cloudy and then a little more and when I brushed, I noticed green algae had settled on the bottom of the pool.

    I don't want to have to keep SLAM'ing it. It seems excessive and it also makes it so that people can't use the pool.

    Any help would be greatly appreciated.

    *** as a side note, even when the pool was really clear and nice, I noticed while underwater with googles on that I could still see what looks like tiny white particles floating everywhere. Not sure what that is, in case anybody knows what I'm talking about.


    thanks!
    10,000 Gallon In-ground pool.

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    JasonLion's Avatar
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    Re: Algae is always coming back

    With CYA at 65, shock level is 26. If you are in the process of fighting algae, you should raise FC to 26 and keep it there until the algae is gone. See SLAMing you pool in the How To section of Pool School.

    Also, your high FC level is probably throwing off the PH test a little. I wouldn't adjust the PH until you have a new PH measurement when FC is below 10.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Richard320's Avatar
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    Re: Algae is always coming back

    Don't forget to toss pool toys, tools, and covers in the SLAM water to kill any lingering algae spores you may have reintroduced.
    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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    Re: Algae is always coming back

    I don't want to have to keep SLAM'ing it. It seems excessive and it also makes it so that people can't use the pool.
    Well, I'm not sure what the alternative would be. What are you thinking would be a good course of action?
    Dave S.
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    Re: Algae is always coming back

    Quote Originally Posted by aonis View Post
    Hi everyone,
    As soon as it was clear I was keeping the FC around 5-7ppm as a constant.

    thanks!
    Were you targeting 5-7 with your dosing or were you not letting it drift below 5-7 at any point in the day (say dosing to 7 in the morning and it drifts to 3 or 4 by late afternoon)?

    at a CYA of 65 your CL should never (at any point in the day) drop below 5, if it does the algae can sneak in.

    You will need to SLAM to clear it, more importantly look at how you are dosing the pool so it doesn't happen again.

    hope this helps!

    Cheers!

    Chris
    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
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    Re: Algae is always coming back

    Thanks for the responses everyone.

    I will properly SLAM it. I know it's wasteful to just "almost" SLAM it. It just feels like soooo much Chlorine! But I'm just a beginner and it's all really new to me. Is there anything I can do going forward to not have to be testing the pool 1 or 2x daily? Is there no type of weekly maintenance program? It seems like a lot of work and soon I'll be traveling a lot and will have to ask someone to help who definitely doesn't have that kind of time on their hands.
    10,000 Gallon In-ground pool.

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    Re: Algae is always coming back

    Quote Originally Posted by aonis View Post
    Thanks for the responses everyone.

    I will properly SLAM it. I know it's wasteful to just "almost" SLAM it. It just feels like soooo much Chlorine! But I'm just a beginner and it's all really new to me. Is there anything I can do going forward to not have to be testing the pool 1 or 2x daily? Is there no type of weekly maintenance program? It seems like a lot of work and soon I'll be traveling a lot and will have to ask someone to help who definitely doesn't have that kind of time on their hands.
    Oncve the SLAM is over and things settle down, testing once a day or even every other day is usually sufficient. You'll learnm the pool's appetite and know before you test what you'lll see. And when you reach the stage where it's routine to add X amount of chlorine every day, it's a piece of cake to entrust the care to someone else for a few days.
    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!

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    Re: Algae is always coming back

    Another question I had is, what are safe FC ppm ranges to swim in? If the CYA is 65. I know 7ppm is ideal (right?) but what is acceptable?
    10,000 Gallon In-ground pool.

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    Re: Algae is always coming back

    Up to slam level but not over.
    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 is always coming back

    Quote Originally Posted by aonis View Post
    Another question I had is, what are safe FC ppm ranges to swim in? If the CYA is 65. I know 7ppm is ideal (right?) but what is acceptable?
    Up to about 25
    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!

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    Re: Algae is always coming back

    That seems so high! Not to sound naive but the pool store people act like I'm crazy if I go over 10ppm. Why is the advice and the methodology so different between TFP and Pool Stores?
    10,000 Gallon In-ground pool.

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    Re: Algae is always coming back

    Quote Originally Posted by aonis
    Why is the advice and the methodology so different between TFP and Pool Stores?
    Marketing and a lack of understanding of the science behind managing pool water chemistry. The typical pool store advice of maintaining a chlorine (FC) level between 1-3 ppm is the best proof of this lack of understanding.

    The first thing a new pool owner should understand is the relationship between chlorine and CYA. The two best resources to begin learning about this are (1) ABC's of Pool Water Chemistry, and (2) Chlorine CYA Chart.
    Gold Supporter, TFP Lifetime Supporter, 26,680 gal Plaster IGP 3.5 - 10' depth / Attached Waterfall Spa, Manually Chlorinated, Triton Sand Filter, 1.5 HP * 1.1 SF = 1.65 SFHP 1-speed Pentair WhisperFlo WF-26 Pump, 400K BTU NG Teledyne Laars Series One Heater, Polaris 360, Test Kit Comparison, Chlorine/CYA Chart, SLAMing Your Pool, OCLT
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    Richard320's Avatar
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    Re: Algae is always coming back

    Quote Originally Posted by aonis View Post
    That seems so high! Not to sound naive but the pool store people act like I'm crazy if I go over 10ppm. Why is the advice and the methodology so different between TFP and Pool Stores?
    http://www.troublefreepool.com/threa...emistry#p50548
    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!

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    Re: Algae is always coming back

    Quote Originally Posted by aonis View Post
    That seems so high! Not to sound naive but the pool store people act like I'm crazy if I go over 10ppm. Why is the advice and the methodology so different between TFP and Pool Stores?
    This is going to sound absolutely snarky ... it is not meant to be at all.

    Here you are dealing with people that have taken the time to educate themselves on the finer points of chemistry (be it in college, through the resources here, or otherwise). In the pool store you are usually dealing with an hourly (possibly seasonal) employee that doesn't own a pool and really doesn't care. Their job is to sell more.
    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 is always coming back

    Point taken!

    I know you guys are experts, was just curious as to why. Appreciate all the replies and the help over the last couple of months. You are all awesome.
    10,000 Gallon In-ground pool.

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    Re: Algae is always coming back

    Quote Originally Posted by aonis View Post
    That seems so high! Not to sound naive but the pool store people act like I'm crazy if I go over 10ppm. Why is the advice and the methodology so different between TFP and Pool Stores?
    seems simple to me,if you take their advice and keep the pool below 11 , then when the algae returns ask them how to get rid of it.

    I opened my pool after fighting algae last fall .FC of 12, 3 hours after opening algae returned. So according to your resources, I should never have gotten a bloom this spring at FC of 12.
    The folks on this site are among the most knowledgeable I have found.
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    Re: Algae is always coming back

    You're totally right. I always go in there and say I'm having algae and they say "well all your chemical levels look good", "just brush and clean your filter more often, have you tried using FLOC?"

    same thing every time. It gets old.

    10,000 Gallon In-ground pool.

  18. Back To Top    #18

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    Re: Algae is always coming back

    Fundamentally, the pool store employees don't understand that in a pool with CYA most of the chlorine is bound to it and essentially inactive. At the minimum FC/CYA ratio recommended for manually dosed pools, the active (unbound) chlorine level is roughly the same as in a pool with only 0.06 ppm FC and no CYA. Even at the shock level, it's still only equivalent to around 0.6 ppm FC with no CYA. Fortunately it doesn't take high levels of active chlorine to prevent algae growth and we set the minimum level to work to prevent green and black algae from growing in virtually all pools regardless of algae nutrient (phosphate and nitrate) level, though we do assume decent circulation of the water.

    The pool industry looking only at the FC level alone and not considering the FC/CYA ratio that determines the active chlorine level is one of the great deceits that keeps the business of using Trichlor tabs and a large variety of specialty chemicals (algicides, clarifiers, flocculants, enzymes, "shock", etc.) going. There is no question that slow-dissolving Trichlor tabs are convenient, but for every 10 ppm FC that they add, they also increase CYA by 6 ppm. Higher CYA levels make chlorine less effective unless you proportionally raise the FC level to keep the FC/CYA ratio constant.
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