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Thread: SLAM duration - how long does it take to kill algae?

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    langerking's Avatar
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    SLAM duration - how long does it take to kill algae?

    My pool has been sparkling clear for almost a full year and it still is. I discovered a tiny amount of visible algae on the white endcaps on my ladder and some around the stair way opening. I also removed my light and found small amounts of algae there.

    As a precaution I started SLAMMING. I have no measurable CYA at the moment, it is <20. Therefore my Shock FC level is only 10. I started the SLAM at 2pm yesterday and this morning at 6:40a.m I passed the OFCL. My loss was only 0.6 since 9:40p.m. the previous night.

    QUESTION: is it necessary to keep on SLAMMING because it has only been about 18 hours since the start and only about 15 since my pool has been at Shock level? I feel like I should hold it at least until tomorrow morning to make sure all algae has been killed.
    1) 21,000 gallons
    2) DE
    3) IG (in ground)
    4) Vinyl
    5) Hayward 1.5 hp DE 3600 72 GPM

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    PAGirl's Avatar
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    Re: SLAM duration - how long does it take to kill algae?

    It probably wouldn't hurt to continue. Brushing again might be a good idea, too.
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    Re: SLAM duration - how long does it take to kill algae?

    I'd brush all the visible algae off, and keep the slam until tomorrow. I'd also get some CYA in the pool today.
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    pwrstrk's Avatar
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    Re: SLAM duration - how long does it take to kill algae?

    I'd keep the SLAM going another day. Like the others said brush everything really good. Do another OCLT tonight. I didn't see a CC test result. What are the CC's. Your done SLAMing when your water is crystal clear, CC's of 0.5 or less, you pass the OCLT.
    You can start adding CYA now or wait till the SLAM is over. I would take the CYA level to 30 then 40. Take it up in steps. 😎
    Jeff
    24'x54" AG Morada RTR (by wilbar) 13'500 gal. Hayward Powerflo Matrix 1hp 2 speed. Hayward Perflex EC65 DE filter.

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    Mod Squad tim5055's Avatar
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    Re: SLAM duration - how long does it take to kill algae?

    Your pool is clear, you passed OCLT but wat is your CC? SLAM until you pass all three

    Is all of the visible algae gone? If not, see the next question.

    Did you brush the visible algae? Algae can be protected from the chlorine by a biofilm that brushing breaks down. If it's there, brush it and continue SLAM.
    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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    Divin Dave's Avatar
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    Re: SLAM duration - how long does it take to kill algae?

    There are 3 criteria for passing the SLAM.
    1. Water is clear
    2. you pass the OCLT
    3. Your CC are < .5

    It would be unusual at best to fully eradicate all of the algae in less than 24 hours, but I supposed it's possible.

    Since you got it in the first place, Sounds like you might need to refresh on a couple of pool school references.
    http://www.troublefreepool.com/conte...ater-chemistry
    http://www.troublefreepool.com/conte...mmended-levels
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    langerking's Avatar
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    Re: SLAM duration - how long does it take to kill algae?

    Quote Originally Posted by buzzard302 View Post
    I'd brush all the visible algae off, and keep the slam until tomorrow. I'd also get some CYA in the pool today.
    OK, thanks! 2 more questions:

    1. Do you think letting it drift back down after tomorrow morning would be good?

    2. Are CYA measurements accurate when you are slamming?
    1) 21,000 gallons
    2) DE
    3) IG (in ground)
    4) Vinyl
    5) Hayward 1.5 hp DE 3600 72 GPM

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    Re: SLAM duration - how long does it take to kill algae?

    Yes, CYA measurement is accurate while SLAMming.
    Someone else will answer the other question.

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    pwrstrk's Avatar
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    Re: SLAM duration - how long does it take to kill algae?

    Quote Originally Posted by langerking View Post
    OK, thanks! 2 more questions:

    1. Do you think letting it drift back down after tomorrow morning would be good?

    2. Are CYA measurements accurate when you are slamming?
    If you mean let your FC drift down, IF you pass all three criteria to stop the SLAM then yes. 😎
    Jeff
    24'x54" AG Morada RTR (by wilbar) 13'500 gal. Hayward Powerflo Matrix 1hp 2 speed. Hayward Perflex EC65 DE filter.

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    langerking's Avatar
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    Re: SLAM duration - how long does it take to kill algae?

    Quote Originally Posted by Divin Dave View Post


    Since you got it in the first place, Sounds like you might need to refresh on a couple of pool school references.
    http://www.troublefreepool.com/conte...ater-chemistry
    http://www.troublefreepool.com/conte...mmended-levels

    I think I got it because I let my CYA get very low and my FC was fluctuating a lot between chlorine treatments (which I only have time to do once a day before work). I was assuming that the CYA would not drop like it did. I measured it frequently for about the first 8 months after starting the BBB method. It never dropped unless I drained and filled huge amounts of water (like at least 6 inches in my pool). Somehow it went from the low 40s to sub 20 in about 3 months and I admit I didn't monitor it thinking it just doesn't move anyway. But we have had a very rainy late spring and summer here in Florida, I had been vacuuming to waste rather frequently and wasn't really tracking the amount of water being replaced.


    Just to be clear, my CC is 0. I wouldn't have said I passed the OCLT unless I meet all 3 requirements.
    1) 21,000 gallons
    2) DE
    3) IG (in ground)
    4) Vinyl
    5) Hayward 1.5 hp DE 3600 72 GPM

    Taylor K-2006
    STA-RITE Great White GW9500

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    Mod Squad tim5055's Avatar
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    Re: SLAM duration - how long does it take to kill algae?

    Quote Originally Posted by langerking View Post
    Just to be clear, my CC is 0. I wouldn't have said I passed the OCLT unless I meet all 3 requirements.
    I don't want to sound harsh/negative but you are confusing a SLAM & OCLT. There is only one requirement to pass OCLT. There are three requirements for the SLAM. I think this was what was confusing folks.

    I wish I had your problems - my CYA is going down painfully slowly with backwashing.

    It would help with answers if you could add your location to your profile.
    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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    langerking's Avatar
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    Re: SLAM duration - how long does it take to kill algae?

    Quote Originally Posted by tim5055 View Post
    I don't want to sound harsh/negative but you are confusing a SLAM & OCLT. There is only one requirement to pass OCLT. There are three requirements for the SLAM. I think this was what was confusing folks.

    I wish I had your problems - my CYA is going down painfully slowly with backwashing.

    It would help with answers if you could add your location to your profile.
    I know what you mean Tim, my CYA was around 300 early last July when I discovered this website and this amazing program with all the great support of members. It took me over 2 months to get it down into the 40s. That's why I was so surprised when I measured what looked like ZERO CYA. I did a double take, tested over and over again. I might break out a new bottle of R-0013 real soon

    Oh, that makes sense now. I was interpreting things incorrectly, that the OCLT meant passing the 3 requirements. But, yeah, I passed all 3 last night. But I am finding it very hard to maintain the Shock level today, at 2:20 when I got home it had dropped to 7.5 (from 10.6 at 10:40). I added a quart of bleach
    4:12 pm 8.0 - added 2 quarts
    5:55 pm 9.5 - added 2 quarts hoping that this keeps me over 10 until sundown, I'll measure again at 7:00 pm.

    I went to the store to buy stabilizer but they didn't have any (Lowe's), my pool store had closed already. I really thought that I was going to be able to get my CYA up with the Trichlor pucks I have been using since I discovered my low CYA problem.
    1) 21,000 gallons
    2) DE
    3) IG (in ground)
    4) Vinyl
    5) Hayward 1.5 hp DE 3600 72 GPM

    Taylor K-2006
    STA-RITE Great White GW9500

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    Re: SLAM duration - how long does it take to kill algae?

    Quote Originally Posted by langerking View Post
    I Went to the store to buy stabilizer but they didn't have any (Lowe's), my pool store had closed already. I really thought that I was going to be able to get my CYA up with the Trichlor pucks I have been using since I discovered my low CYA problem.
    Walmart has it too.
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