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Thread: do i need floc or algaecide

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    do i need floc or algaecide

    Hi,
    *** Changed sand to start this year***I have been stumped..HAve a green *dust on bottom of pool. I have tried vacum to waste, and that helps for abit. Sunday here (zip 61822) lots rain, vacum again to waste.brushed a lot
    Before adding pressure was 15...Ive added DE 1/2 cup to start. Reading went to 18 or so and return flow went way down and skimmer basket floating ( no suction) I backwashed and wattched water clearity until clean + some. As soon as I return to filter with increase flow... the jet starts out with that green mist. The sand, is it not catching the small particles?
    Question: Do I proceed with floc alone or do I use algaecide first? Or a combo of both.
    As always the info on here is soooo helpful. Just can not seem to get this figured out...


    FC: 8
    PH: 7.3
    TA: 180
    CH: 250
    CYA: 50


    18,400,AG,sand Pentair SD60,dynamo 1.5hp
    Taylor K-2006.
    18,400,AG,sand Pentair SD60,dynamo 1.5hp
    Taylor K-2006.

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    DaninFLA's Avatar
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    Re: do i need floc or algaecide

    have you done a OCLT to verify if its algae? raise your FC to 15 or so tonight and do the OCLT and report back. algae isn't a filtering problem, its a chlorine problem. if you pass the OCLT, then you probably have a pollen problem.

    Do NOT add algaecide and/or floc

    also, need to follow the DE guidelines, I believe you only add enough to raise your pressure 1 psi. that's how you know you added enough DE. then you backwash your filter when it rises 25%
    Dan
    9,000 gallon in-ground Saltwater pool, plaster, cartridge filer, 1.0 hp pump, Hayward T-15 SWCG, TF-100
    Pool School - Chlorine / CYA Chart; Pool School - Test Kits Compared;

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    Texas Splash's Avatar
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    Re: do i need floc or algaecide

    I'm with Dan. Generally speaking, without specific circumstances or reasons to think otherwise, we don't typically rely on Floc or algaecides. While your numbers above appear to be solid, is it still possible that your FC may have dropped at some point just long enough to develop algae? At least that's what it looks like from your description which would indicate the need to Pool School - SLAM - Shock Level And Maintain. Also, I don't see your CC reading above, so providing that may help.

    Have you considered doing an Pool School - Perform the Overnight FC Loss Test (OCLT) just to confirm?

    Adding other chemicals may introduce new problems you don't want.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
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    Re: do i need floc or algaecide

    Thanks.
    I will do this tonight and look forwad to the results
    18,400,AG,sand Pentair SD60,dynamo 1.5hp
    Taylor K-2006.

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    Re: do i need floc or algaecide

    Night reading was 7.0 on FC... Morning reading was 6.0. So a loss of only 1.0. by definition no living algae.
    Apologizes on the wrong CH number. Hmmm now what..? Not unlike anyone else, we want that crystal blue water... Haven't been able to achieve it here this season.
    Our yard gets a lot of shade with mature trees around it. Sun comes late in day, around 2:30 or so. and lasts maybe 3 hours until it goes behind neighbors trees. Does this fact make a difference?
    Im gonna keep on with vacuuming and holding numbers. I will look at what's needed to get the CH changed.


    FC:6
    PH:7.4
    TA:180
    CH:90--was wrong in initial reading... looked at wrong number.90 in accurate
    CYA:30
    18,400,AG,sand Pentair SD60,dynamo 1.5hp
    Taylor K-2006.

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    Re: do i need floc or algaecide

    Might be a good idea to check your CYA numbers again. Originally, you posted 50 as your number then 30 this morning. No way to lose that much CYA without significant water replacement.
    33 Round AGP, 26K gal, vinyl liner, 1 HP single speed pump, 1 Hayward wide mouth skimmer, Pentair sand filter, Taylor K-2006 test kit, Red Leopard Orbit suction auto vac, Pool School, TFTestkits, PoolMath, Support this Site!

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    Texas Splash's Avatar
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    Re: do i need floc or algaecide

    Interesting scenario. I agree that you may want to double-check your CYA since you won't just lose 20 ppm of CYA like that. When you check, wait until the sun comes-up today and keep that bright sunlight at your back and the tube at your waist as you watch for the black dot to disappear. After you do a reading, you can pour the mixture back into the mixing bottle and re-test immediately again just so that your eyes can relax/re-focus. I sometimes check mine 2-3 times just to be sure. Also, next time you post some readings, also include the CC (combine chlorine) as well. That tells us more stuff we need to know.

    As for the green "dust", I'm assuming you still have it right? If so, it's still possible that it's algae. I had it like that at one time. So if you don't see any improvement through filtering, you might still consider doing a SLAM: Pool School - SLAM - Shock Level And Maintain. Remember, the key there is to "maintain" that higher FC level based on the Pool School - Chlorine / CYA Chart. Follow the SLAM page carefully and you should complete your SLAM is a decent time frame since your pool doesn't appear to be terribly bad, and your CYA is relatively low requiring less bleach. You may be asking, "Why SLAM if my OCLT passed?" Well, while the OLCT limit is 1 ppm, whenever we reach that max during the test, we have to be critical and take everything into consideration (i.e. condition of the water, CC readings, is there ANY chance my count was off or the reagent drops did not flow in a standardized manner). Personally, I've been so close on my morning portion of the OCLT test that I did it twice and came-up with two different results. But there's little room for error, so I was very critical on myself.

    Anyways, those are some items for your to consider. Let us know if you have any other thoughts or concerns.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
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    jeffchap's Avatar
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    Re: do i need floc or algaecide

    With a lot of trees as you describe, any chance that it's tree pollen instead?
    25000 gallon free-form gunite
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    Mod Squad tim5055's Avatar
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    Re: do i need floc or algaecide

    I agree with Pat. While a 1.0 ppm loss on the OCLT is technically a pass, combined with the "dust" that keeps appearing makes me think you are holding a full algae bloom at bay with your current FC level. I would SLAM the pool.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    ship of fools's Avatar
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    Re: do i need floc or algaecide

    An overnight loss of 1.0 is at the limit of acceptable numbers and i know i have read that it is more meaningful with higher chlorine readings. For example a loss from 19 down to 18 is ok but when you are starting low and still lose 1 ppm you may find you do have algae. Since the OCLT was close and you are having issues i would SLAM it and eliminate algae as a potential issue.
    21,000 gallon inground
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    DaninFLA's Avatar
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    Re: do i need floc or algaecide

    Quote Originally Posted by pool603vac View Post
    Night reading was 7.0 on FC... Morning reading was 6.0. So a loss of only 1.0. by definition no living algae.
    Apologizes on the wrong CH number. Hmmm now what..? Not unlike anyone else, we want that crystal blue water... Haven't been able to achieve it here this season.
    Our yard gets a lot of shade with mature trees around it. Sun comes late in day, around 2:30 or so. and lasts maybe 3 hours until it goes behind neighbors trees. Does this fact make a difference?
    Im gonna keep on with vacuuming and holding numbers. I will look at what's needed to get the CH changed.



    FC:6
    PH:7.4
    TA:180
    CH:90--was wrong in initial reading... looked at wrong number.90 in accurate
    CYA:30
    a 1ppm loss at that low of a FC is not the same as a 1 ppm loss when you are at 15-20ppm. you lost 1ppm from 7ppm...that's a 14% consumption of FC. you might have an algae problem. If you lost 1ppm when your starting FC was 20, that's only 5% loss. see the difference?

    re-do the test as recommended. do not do anything lower than 15ppm. you also need to post if you had any CC in the morning.
    Dan
    9,000 gallon in-ground Saltwater pool, plaster, cartridge filer, 1.0 hp pump, Hayward T-15 SWCG, TF-100
    Pool School - Chlorine / CYA Chart; Pool School - Test Kits Compared;

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    Re: do i need floc or algaecide

    Quote Originally Posted by DaninFLA View Post
    a 1ppm loss at that low of a FC is not the same as a 1 ppm loss when you are at 15-20ppm. you lost 1ppm from 7ppm...that's a 14% consumption of FC. you might have an algae problem. If you lost 1ppm when your starting FC was 20, that's only 5% loss. see the difference?

    re-do the test as recommended. do not do anything lower than 15ppm. you also need to post if you had any CC in the morning.
    +1

    You should really be at or slightly above your shock level per your CYA when doing an OCLT.

    The three criteria of a successful SLAM is:
    1) The water is CLEAR
    2) OCLT <1.0ppm
    3) CC <0.5ppm

    You are:
    1) Cloudy
    2) Marginal to fail
    3) Unknown

    I would bump my FC to 15 just before sundown, check FC when the sun is down (at least a 1/2 hour after adding) & recheck in the morning an hour or so before sunup.

    Good Luck

    Dom
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