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Thread: Not getting Algae and FC ideal levels

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    Not getting Algae and FC ideal levels

    CYA (Stabilizer) Minimum FC Target FC Shock FC
    60 5 7 24

    I assumed from this chart that if you keep FC between 5 and 7 you won't have algae.

    However I have found algae can grow well at 7 FC. Yes can treat with shock, again,
    but would rather understand why. Is it better to have a higher target FC level, say
    12 FC. Would that buy me less algae?

    My current thoughts, please advise if any/all need correction:

    -- algae will not grow at FC 24
    -- algae grows rapidly if FC under 5
    -- at first sign of algae, bump FC to 14 and run pool cleaner each day til no visible algae
    -- FC above 10-12 is not well liked by swimmers
    36K gal, gunite w/ plaster,[18W x 38L x 8 deep end] 300SF cartridge, 80-100 GPM filter, Sta-rite S7M120 and Polaris 9300 electric robot. Rooftop 6 panel Solar heater, Sacramento Valley, Climate Zone 8

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    Mod Squad jblizzle's Avatar
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    Re: Not getting Algae and FC ideal levels

    Have you run the shock process to completion by passing the 3 criteria to stop?
    Did the FC ever drop below 5ppm?
    Where is the algae showing up?

    If you "sterilized" your pool and never dropped the FC too low, then algae should not have reappeared ... unless maybe if it was mustard algae only showing up in the shady areas.

    At a first sign of algae you should go through the entire shock process.

    To your last point ... swimmers will have no idea how high your FC level is. If it is less than shock level and greater than the minimum for your CYA, it is safe to swim and likely not noticeable.
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    Re: Not getting Algae and FC ideal levels

    To get the concepts down and why shocking is a "process" and not a one time application you have to understand that algae growth is exponential. 1 becomes 2, becomes 4, becomes 8, etc. Maintaining your FC at recommended target levels for your CYA kills the individual cells at a rate that is faster then their reproduction - this means it never really "grows".

    The reason for the shock PROCESS is to bump the FC to levels (and HOLD there until you pass all 3 criteria in shock PROCESS) that aggressively breakdown the algae cells at such a rate they simply cannot increase the population in any way and eventually the entire population is dead. It's a chemistry thing, overcome the exponential growth of algae - destroy it at a rate, by time, that is greater than they can reproduce.

    Once the population is so small, they can never reproduce fast enough to overcome the levels of your target FC.

    If you follow the methods here, never let FC drop or get to min, with accurate testing you will never get visible algae, and if you do you perform the shock process. Visible algae means you need to go through the shock process.

    To your ultimate question - YES, algae can grow with your target FC level if the population reaches the point you have visible algae. If you can see it it's already ahead of you and hence the need for the shock process. Maintaining your target FC and never, ever, ever let it get below MIN means you stay ahead of it's growth rate. There are all kinds of organics, algae, cells in your pool (note I say individual cells, they don't last long) - the point of maintaining target FC level is they never get a chance to increase the population and will quickly die.

    I just thought of a good analogy. You've got a 1 acre lot and a push mower. The algae is the grass, your mower is the chlorine. You only have 2 hours per day to mow and can do no more (remember chemistry and exponential population growth is based on time).

    You have burned your lawn down by following the shock process. But hopefully you keep running the mower over the lawn (by constantly maintaining FC levels) even if you see no grass and it knocks down any little shoots that sprout up. They can't send out runners or do much else as you keep cutting them to the ground.

    You fall asleep for a few days and see grass growing, you hit it with the mower but your time is up and 1/8 of the yard has grass. You go out again tomorrow and mow that 1/8 only to find the other 7/8 has grass. So you attempt to mow the entire lawn but the grass is now making you move slower as you're cutting more.

    Since you've only got 2 hours to mow the grass is now growing faster than you can cut it, your mower is bogged down and you can't even cut 1/4 of the lawn in your time. Notice you've been keeping your FC levels at recommended levels and mowing the same time, but yet it grows.

    Time to follow the shock process. The shock process is a bush hog, in the same amount of time 2 hours but knocks the grass down. You keep using the bush hog and the grass is knocked back to a point it is barely sending up shoot. You go back to your regular mower (target FC).

    Yes, algae can grow at target FC levels but it depends on how much there is. The point is to prevent it from having a population that can outpace your chlorine levels.
    18x36 inground vinyl lined, Hayward sand filter and tablet chrolinator, approx 18k gallon

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    Re: Not getting Algae and FC ideal levels

    It also depends on the type of algae. The Pool School Chlorine / CYA Chart is set to prevent green and black algae growth in pools with good circulation. It will not prevent yellow/mustard algae growth in a pool with sufficient algae nutrients. To do that would require an FC that was at least 15% of the CYA level and since that can be impractical due to the higher daily chlorine usage required, most people shock their pools with a high enough FC level and get behind light niches and under removable ladders and put in poles and other equipment to completely get rid of this more resistant form of algae.

    I used to say that the failure rate for these target levels was less than 1 in 5000, but given the larger population of users and indirect reports from pool services following these methods it's more like 1 in 10,000. So there might be some rare form of green algae not killed quickly enough, but more likely it's poor circulation or the reports aren't accurate such as the FC not actually at a certain minimum or the CYA level being higher than reported.

    So please tell us more about the algae that you have found. What color is it -- green, black, yellow/mustard? Is it clumpy/slimy or more like dust? Is it only in the shady areas of the pool or elsewhere? Is it possible to be pollen accumulating in areas of low circulation? How is the circulation in your pool -- do you have an operational floor drain? How many skimmers? How many returns?
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    Re: Not getting Algae and FC ideal levels

    I don't know about operational. first time with pool and pool inspectors both postponed, busy season I guess.

    Operational floor drain, one return/skimmer, I think, but not at all sure. when I turn on the pump bubbles come up in the pool drain and 4 sides.

    Unfortunately I did let FC drop. Now I've started a sheet and plan to check FC/PH daily and rest once a week.

    Algae is all on the east side, which is in shade until about 11am.. It's kind of a milky green. very soft and seems like it would fall off with a little brushing. No I don't have a pool brush yet. It disappeared at last shock, completely. But returned. My FC was very low and it was spreading, today it was at 7 and plan to bring it at least to 10 tomorrow. [all the chems I have on hand]. Since leslie sold me some phosphate stuff, I thought I might was well use it tomorrow. Sat I"ll check and if not gaining ground, will get enough shock to get it all.

    BTW, I found it is normally very very hard to transport shock in a car. Even with windows open the gas is too much, and that is for a short 1 mile drive. Solution is to put the shock gallons in garbage bag and seal it. no problems on drive home, naturally the windows are still all the way down.

    Not pollen, we had a lot of that earlier. It's like dust. Oh the "shady side" in the morning is of course the sunny side in the afternoon, humm, excellent light, excellent growth.

    I don't think the rubber scrubbers of a robotic cleaner touch this stuff. It may disturb it a bit, but not remove.

    Excellent information from all of you, thank you!!!
    36K gal, gunite w/ plaster,[18W x 38L x 8 deep end] 300SF cartridge, 80-100 GPM filter, Sta-rite S7M120 and Polaris 9300 electric robot. Rooftop 6 panel Solar heater, Sacramento Valley, Climate Zone 8

  6. Back To Top    #6

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    Re: Not getting Algae and FC ideal levels

    Quote Originally Posted by Notri4MeBikeSwim
    BTW, I found it is normally very very hard to transport shock in a car. Even with windows open the gas is too much, and that is for a short 1 mile drive. Solution is to put the shock gallons in garbage bag and seal it. no problems on drive home, naturally the windows are still all the way down.
    I presume you mean gallons of chlorinating liquid. You might try tightening the caps before you put them into your car. I find that they are often a bit loose when I buy them and would tend to smell if I didn't tighten the caps. On the other hand, the caps are designed for pressure-release so if the car gets hot or the gallons are exposed to the sun (best not to do, if possible), then the pressure can cause gaseous release.

    Is your plaster white? If it were tinted blue then yellow algae might look green. The algae you describe seems to have some of the characteristics of yellow/mustard algae, though not all of them so just trying to get more definitive.
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    Re: Not getting Algae and FC ideal levels

    Yes, gallons of double strength bleach, marketed as "shock". The caps weren't loose, just vent a lot.

    Interesting, yes the pool plaster is about the pale blue of the background color on this forum.

    As suspected FC dropped over one day, by 1.5. So added 3 gallons this morning. That should raise FC by about 3 numbers. Probably not enough to deal with the algae, but need more chemicals.

    Reread the directions on the phosphate+ [Leslies product] and says works best with FC at 5. 5 just doesn't work on our pool, it's too low. I'm guessing my last shock really knocked down the algae but did not eliminate it and was just dormant for a bit and then exploded.
    36K gal, gunite w/ plaster,[18W x 38L x 8 deep end] 300SF cartridge, 80-100 GPM filter, Sta-rite S7M120 and Polaris 9300 electric robot. Rooftop 6 panel Solar heater, Sacramento Valley, Climate Zone 8

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    Mod Squad jblizzle's Avatar
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    Re: Not getting Algae and FC ideal levels

    Why are you worrying about the phosphates? They do not matter if you maintain adequate FC.
    Jason, TFP Moderator
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    Re: Not getting Algae and FC ideal levels

    Not worrying about it, just bought it, so might as well use it.

    Didn't have the computer with me, but looked again in the bright light. Here's the closest
    http://www.valsparpaint.com/en/explore- ... rt%20paint

    fresh pear 6007-7C
    temptation 6007-8B
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    Mod Squad YippeeSkippy's Avatar
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    Re: Not getting Algae and FC ideal levels

    Quote Originally Posted by Notri4MeBikeSwim
    Not worrying about it, just bought it, so might as well use it.
    Acccccck! That's a horrible reason to use it in the pool, especially since apparently phosphates are not an issue to worry about usually. Why add any chemical to the pool unnecessarily?

    If you're concerned with the waste of money it was buying it, try and take it back and see if you can return it or at least exchange it for something actually needed.
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    Re: Not getting Algae and FC ideal levels

    Ok, reading some past articles and assuming I have mustard algae

    1- need to shock at higher levels AFTER dropping PH to 7.0; initially only at shock value, not shock +15%
    2- need to scrub the shady walls where there is less water circulation
    3- after/during shock need to scrub the walls
    4- need to rinse off fully if swimming during these higher LC times

    Question: should I add borates? if so, how much?
    36K gal, gunite w/ plaster,[18W x 38L x 8 deep end] 300SF cartridge, 80-100 GPM filter, Sta-rite S7M120 and Polaris 9300 electric robot. Rooftop 6 panel Solar heater, Sacramento Valley, Climate Zone 8

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    Mod Squad YippeeSkippy's Avatar
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    Re: Not getting Algae and FC ideal levels

    Quote Originally Posted by Notri4MeBikeSwim
    Ok, reading some past articles and assuming I have mustard algae

    1- need to shock at higher levels AFTER dropping PH to 7.0; initially only at shock value, not shock +15%
    2- need to scrub the shady walls where there is less water circulation
    3- after/during shock need to scrub the walls
    4- need to rinse off fully if swimming during these higher LC times

    Question: should I add borates? if so, how much?
    I kinda doubt you're anywhere near a point to consider borates if you've still got other chemistry problems as well as a limited understanding of the BBB methods. I would suggest you keep referring to Pool School articles to review the basic chemistry of pools.
    My Amazon Smile for November12K Fiberglass IG, Infinity 4000 automatic cover, SWCG, Hayward Sand Filter, Hayward 1.5 Pump, Doheny Discovery Robot, Savi Melody LED pool lights, outdoor speakers and other assorted doo-dads. Sundance Altamar Hot Tub.
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    Re: Not getting Algae and FC ideal levels

    ok, FC dropped only normally last night -0.5 FC, I suspected more of a drop with algae. New shock process and new wall scrubber in plans for today
    36K gal, gunite w/ plaster,[18W x 38L x 8 deep end] 300SF cartridge, 80-100 GPM filter, Sta-rite S7M120 and Polaris 9300 electric robot. Rooftop 6 panel Solar heater, Sacramento Valley, Climate Zone 8

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    Re: Not getting Algae and FC ideal levels

    If you keep FC levels at their normal recommended levels you should never get algae. However, if you already have algae, FC at normal levels is quite unlikely to ever kill it all off.

    If you only lost 0.5 of FC overnight then there is no reason to think you have living algae. What is happening that causes you to think you have algae?
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  15. Back To Top    #15

    Re: Not getting Algae and FC ideal levels

    it wasn't a full 24 hours and can see algae like stuff on the side, two days ago it snowed when brushed feet against it.

    Fri am, FC 4.5; added 3 gal CL
    Fri about 5pm, FC 9.5
    Sat am, FC 9.0

    "am" is between 6:30 and 8:00 am
    36K gal, gunite w/ plaster,[18W x 38L x 8 deep end] 300SF cartridge, 80-100 GPM filter, Sta-rite S7M120 and Polaris 9300 electric robot. Rooftop 6 panel Solar heater, Sacramento Valley, Climate Zone 8

  16. Back To Top    #16

    Re: Not getting Algae and FC ideal levels

    Bumped FC up to 24 and overnight it dropped to 14, so hit it again this morning. Definitely had algae, but it's disappearing now.
    36K gal, gunite w/ plaster,[18W x 38L x 8 deep end] 300SF cartridge, 80-100 GPM filter, Sta-rite S7M120 and Polaris 9300 electric robot. Rooftop 6 panel Solar heater, Sacramento Valley, Climate Zone 8

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