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Thread: Prepping to SLAM for the first time

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    Prepping to SLAM for the first time

    Hi all:

    This is my first post, but I've been reading this board religiously for the past 12 months. We are relatively new pool owners; this year, I've appointed myself full-time pool girl, both to save money and to keep on top of issues. Last summer was a series of disasters: the pool had two leaks (which took a month to detect), we had to add about 8" of well water during that time, which added a lot of iron to the water (we cornered the market on sequesterant) , our SWB cell died and our heater decided to stop working. All this, and I had to wait on our pool company for answers or analysis or attention. As a result, we spent a lot of money on a pool that we rarely used. (Upside: our sand filter has new sand, we have a new SWG cell, our heater has a new pressure switch and will get a new gas value next week, and we have no leaks this spring.)

    Our pool was opened two weeks ago. Initially, the water was clear and blue. I added chlorine (dichlor) and brought the TC levels up to normal levels. (I didn't have my TK-2006 kit yet, only my Pentair Rainbow.) Water went cloudy but stayed a beautiful shade of blue. Now, the water is clearer but definitely green and there's a strong chlorine smell. After all the reading here, I know what that means. I am preparing to SLAM the pool, but I have some questions before I get started.

    1. Our water is still pretty cold; in the 50s, I would guess. As a result, our SWG is off still. Does that mean I should SLAM at the level for a non-SWG pool?

    2. I got my TK-2006 this afternoon and tested. Here's what I found:
    FC = .2
    CC = .8
    CYA = 30
    PH = 7.6
    Given those readings, and the fact that I have some dichlor here, would anyone recommend I SLAM with the dichlor? I was surprised to find my CYA so low, since I've used several rounds of stabilized dichlor already. And I'm not too worried about my PH going high temporarily. Last summer, I added jugs of muriatic acid to lower it. Our water seems to tend toward the higher end of the PH scale naturally. (Maybe because of the SWG?)

    3. This is looking ahead, but does it make sense to wait and turn on the SWG a few days after I turn on the heater? I'm in Minnesota, so the water warms very slowly without a heater, and my understanding is a SWG doesn't work effectively with cool water.

    Many thanks!
    40,000 IG vinyl pool / sand filter / SWG / Intelliflow VS / TK-2006 / well water / sunlight blocking cover

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    Mod Squad jblizzle's Avatar
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    Re: Prepping to SLAM for the first time

    Welcome to TFP!!!

    1. The shock FC level is the same regardless whether it is a SWG pool or not. The level is just a function of your CYA level.

    2. I would not use Dichlor because then your shock FC is going to rise with the rising CYA. After you are done with the SLAM, you could use the Dichlor for normal maintenance to raise the CYA while the water is cold before the SWG will work. What is your TA? If that is high in conjunction with the SWG, your pH may raise pretty quickly.

    3. Leave the SWG off until the slam is complete and the water is approaching the 70s.

    - - - Updated - - -

    Also, for the FAS-DPD chlorine test, use 10ml of water instead of 25ml. Then each drop is 0.5ppm and you will not run out of reagent as fast. Although you might want to order the refills for the FAS-DPD and CYA tests now as the K-2006 is pretty stingy. You can get them a tftestkits.net
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
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    Re: Prepping to SLAM for the first time

    Thanks Jason. I will definitely order some refills for the FAS-DPD and CYA tests.

    So, if I'm reading the Pool Calculator right, I should add 734 ounces of 6% bleach to raise my FC from .2 to 12, right? And then, according to Pool School, I should monitor my FC and keep it at 12 until the water is clear, my CC is under .5 and my pool can hold the FC relatively well overnight?

    One last question: since we have an automatic cover, what are the ramifications of closing the cover while SLAMMING? At some point, we were told excess chlorine fumes could weaken the cover. We aren't expecting much sun this week, but I'm worried about the rain in the forecast.

    One more! Will SLAMMING harm a pool vacuum? Or does it need to be removed before SLAMMING?

    Kelly
    40,000 IG vinyl pool / sand filter / SWG / Intelliflow VS / TK-2006 / well water / sunlight blocking cover

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    Mod Squad jblizzle's Avatar
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    Re: Prepping to SLAM for the first time

    That is what PoolMath is telling me, well 736 oz Are you sure it is 6%? Most bleach is now 8.25%.

    Just lower the pH to the lower 7s before raising the FC, but sounds like you understand the process.

    Usually you do not want the cover on all the time during a SLAM, let the pool get some sun everyday if possible to help break down the CC.

    The higher FC level are more harmful to things than the maintenance levels, but the SLAM method does not really raise the active chlorine level high enough to really damage anything ... unlike some pool store methods where they have you raise the level to astronomical levels 1 time.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
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    Re: Prepping to SLAM for the first time

    THANK YOU!

    Are there any general guidelines for how long a SLAM should take - i.e. how many gallons of bleach I should have on hand?
    40,000 IG vinyl pool / sand filter / SWG / Intelliflow VS / TK-2006 / well water / sunlight blocking cover

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    Mod Squad jblizzle's Avatar
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    Re: Prepping to SLAM for the first time

    Not really any general guidelines, depends on what is in your water. I would start with 2-3 times the amount needed to get you up to shock FC level initially.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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