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Thread: First attempt at SLAM but not sure...

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    Join Date
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    First attempt at SLAM but not sure...

    My first post, but I've been reading and reading and found so much helpful info on this forum. Thank you. I have a degree in chemistry, so I do understand the technical parts of pool chemistry, but since I've never put TFP/BBB into practice, this is new to me.

    I have to start by saying my pool is very clear, but I think it's by luck. All summer my FC and TC has been testing at zero. Because my former pool supply place had me convinced I needed to add more granular shock and Cl tablets (I know better now!) I was a shock junky and dumped pound after pound of dichlor in my pool weekly. After finding TFP and reading, I realize it's because my CYA is way too high. I bought a Taylor 2006 test kit and the CYA was about 100 (I'm still kind of fuzzy on exactly how opaque the test sample has to be to not see the dot...I think I'm imagining I'm seeing it when I probably don't). So last week we bought a pump and pumped out the upper hot water (about 88 degrees) for two days, while refilling it at the bottom with cold water from the well. I expected the temperature gradient to keep the CYA water separate from the clean water.

    After pumping I tested the CYA and it is about 80. I know that's high, but our well needed a break and I really needed to get chlorine in the pool (this may be where my mistake lies, which is why I'm asking you.)

    So I went ahead and started the SLAM yesterday afternoon.

    Initial test:
    pH 7.7
    FC 0
    TC 0
    TA 120
    CH 160
    CYA 80

    Using the CYA/Cl chart and the pool calculator, I put in a little over 6 gal of 10% liquid chlorine.

    After a few hours I tested again and my FC was down to 8. SLAM says to bring it back up to shock level, so using the calculator again, I added another 5 gal of chlorine.

    Tested again this morning and the FC is down to 3. I'm supposed to add another 6 gal of chlorine.

    So my questions are
    1) Do I just keep using the pool calculator and keep adding more chlorine? According to the calculator, I need to add another 6 gal. I know the CYA is high, so is this normal numbers for a clear pool? There are no signs of algae.

    2) Does the Cl bonded to CYA show up in the TC test, or is the TC just the FC plus the chloramines? I don't understand why I initially had zero TC when I initially was shocking and using Cl tablets.

    3) Do I truly need to forget about SLAMing and just get my CYA down?

    4) Short of running the pump again for a few days, do you have any other suggestions?

    Thank you all so much! And if there is more info on my pool that you need, that I haven't put in my signature line, please let me know! (I'm a newbie, obviously!)

    Petrie
    Southeast US, In ground, vinyl, 18'x36', 22,000 gal, sand filter, Hayward Cl feeder (presently empty)

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    Mod Squad woodyp's Avatar
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    Re: First attempt at SLAM but not sure...

    Welcome to the forum. With the great test kit you have, you've already proven to yourself that SOMETHING IS CONSUMING YOUR CHLORINE. Clear water or not, you have not passed all 3 criteria of the SLAM until you pass the OCLT part of it. FC+ CC = TC
    Maintain that SLAM FC number as best you can with more frequent FC additions if possible. You didn't mention having brushed your pool. Don't get lazy on us! Keep the pump running 24/7 and the filter cleaned during the process.
    16x32x52" Steel Cornelius Miramar AGP Vinyl liner 13,100 gal. Buried 2 ft.
    2 Speed Hayward Power-Flo Matrix 85 g.p.m. 22" 250lb. sand filter hard plumbed
    Pool Rover Jr., Pool Blaster Max, Diver Dave TF100 Test Kit/Speed Stir
    Margaritaville Frozen Concoction Maker, Liqour Chiller, & Drink Mixer & Party Tub----Collect 'um all!

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    Re: First attempt at SLAM but not sure...

    Yes, I have brushed after each chlorine addition, and the pump runs 24/7. I backwashed prior to the SLAM. So if all else looks like I'm proceeding correctly, I'll just keep pouring in the bleach. Thanks!
    Southeast US, In ground, vinyl, 18'x36', 22,000 gal, sand filter, Hayward Cl feeder (presently empty)

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    Re: First attempt at SLAM but not sure...

    Oh, just realized a possibly confusing point in my original post...question 4 was asking about pumping more water out of the pool, not about running my regular filter pump. That stays on 24/7.
    Southeast US, In ground, vinyl, 18'x36', 22,000 gal, sand filter, Hayward Cl feeder (presently empty)

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    Re: First attempt at SLAM but not sure...

    I'm still SLAMing (started Friday afternoon and now it's Sunday evening) and the FC continues to drop to as low as 12ppm when my shock goal is 31 ppm. I've added at least 36 gallons of bleach. Just keep going until I maintain 31 ppm? This is mind-boggling to me.
    Southeast US, In ground, vinyl, 18'x36', 22,000 gal, sand filter, Hayward Cl feeder (presently empty)

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    Re: First attempt at SLAM but not sure...

    If your target FC is 31 why are you letting FC drop as low as 12? It's imperative during a SLAM that you keep the FC at target or better at all times. If your FC has dropped to 12, it was below target for HOURS, essentially making you start over. Everytime the FC is allowed to drop below SLAM level for an extended period of time, you are letting algae multiply again and the end result is starting over, which after 36 gallons is likely what you've been experiencing.

    I don't know what your water fill situation is, but if economical, you might consider a water exchange to get the CYA down to a more manageable 40 or 50.
    18' x 38' Pool, 3' to 8' Depth
    Vinyl Liner
    SWG
    Variable Speed Pump
    Sand Filter

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    cj3737's Avatar
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    Re: First attempt at SLAM but not sure...

    +1

    How often are you testing you FC? During a slam its should be every couple hours at most... You have to try to maintain that shock level best you can.. IF you have to leave for a bit, add enuf to get a bit over your shock target to hold you over

    To answer your questions...
    1. Yes.. keep using pool math.. its amazing and very accurate
    2. The CYA bond doesn't show up... Testing CYA is just so we know what FC level to target. Any FC very much above recommended levels is just a waste as the sun will burn that off in a heartbeat. Don't worry about TC with TFP.. All that matters is the FC and CC levels..
    3. Since you are already a few days in, keep going... maintaining the level is easier if you keep up on it. When I started my slam, I tested every hour and added what I needed rather than letting it drop and adding gallons at a time.
    4. Keep pump running for the whole slam.. Brush/vacuum regularly.. turn off water features and SWG while slamming.. Clean skimmer basket or any other filters to keep the water flowing..

    Other than that, it sounds like you are well on your way!! Keep at it!!!
    Inherited 24' Muskin Above ground
    13500 gal
    Hayward S180T92S Sand filter
    Taylor K-2006C Speedstir
    TFPC for Beginners | Pool Math | Pool School | CYA Chart | SLAM | Test Kits | ABC's

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