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Thread: Will a new Variable speed pump change SLAM process

  1. Back To Top    #1

    Join Date
    Jul 2016

    Will a new Variable speed pump change SLAM process

    My old single speed pump stopped working last month and Leslie's installed a new Pentair Variable speed pump for me. Currently it is running at highest speed from 12 pm to 5 pm and at just skimming the surface at other times. The pool had turned green while the pump was not working. I got it back to blue. A few days later it agained turned green, (we had a couple of thunderstorms and heavy rains) right before the long weekend. The CYA when tested was zero, so I added 7lbs to the skimmer (should raise CYA level by 60 by my calculation) and then followed SLAM process. A week later CYA was registering in 30-40s and pool was a murky gray with lots of turbidity. Since a week had passed since adding CYA I backwashed to get the pool crystal clear. 3 days later, bam CYA back to zero and a green pool. The extremely high temperatures are not helping. This has never happened before when i used to keep my old pump running for 24-48 hrs after SLAM process and adding CYA. So I'm worried that the new pump is affecting the process.

    Here are my questions:

    Will the speed running at highest level for just 5 hrs significantly decrease the CYA dissolve rate? With old pump, I backwashed after a week with no issues. Should I give more time between backwashing for variable speed pump? Then I get into the pool not filtering adequately conundrum. Should I use the CYA sock method? Does the CYA dissolve when the water is just passing through the filter at lowest rate?

    The cleaner works only when pool is at highest speed setting. Is that significantly affecting the cleaning rate? Can I put cleaner to work when pump at lowest speed?

    Previously I have always got my pool back to blue in 48 hrs and this is really worrying me.

    Also how do I proceed now?

  2. Back To Top    #2
    Mod Squad Texas Splash's Avatar
    Join Date
    Jun 2014
    South-Central Texas, Marion/San Antonio

    Re: Will a new Variable speed pump change SLAM process

    Hello and welcome to TFP! Well, I can just about bet your problem is not the filter, it's your chemistry. You mentioned attemping a TFP "SLAM" (link below) but I'm not so sure you actually did it correctly. So let's highlight a few things:
    - What test kit are you testing with? That's #1.
    - CYA doesn't just disappear, it only goes lower after substantial water exchange, so something else is happening which is why we need to know how you are testing.
    - A higher flow rate from the pump won't resolve the algae; it's all about the proper CYA/FC ratio as noted on the Chlorine/CYA Chart (link below).
    - A SLAM can take several days to a week or more to pass all 3 SLAM criteria.
    - For CYA, yes - the sock method works best with granular stabilizer

    So we have a few things to confirm/adjust to help you. Get back with us about your test kit and any other questions you may have and we'll try to get you back on course. Nice to have you with us.
    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
    If you enjoyed your TFP experience, please consider donating to Support TFP!

  3. Back To Top    #3

    TFP Guide

    Join Date
    Jul 2015
    Central Valley CA

    Re: Will a new Variable speed pump change SLAM process

    Welcome to the forum! I think Texas Splash has you sorted. I just want to reiterate what he said "CYA doesn't just disappear". I would not add more until we can figure out why the testing is showing a decrease.
    12,300 Gallon, IG PebbleFina, built Oct 2015, 3 ft sheer, 2 Jandy nicheless LED lights, Jandy Pro 1.5HP VS pump (A.O. Smith Motor), PB4-60 Booster pump, Polaris 280, Jandy cv340 cartridge filter, Zodiac z4 control panel W/iAquaLink, 10GPDStenner for chlorine, 3GPD Stenner for MA, TF-100.

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