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Thread: Shock or not to shock?

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    tcat's Avatar
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    Shock or not to shock?

    Been DIY for 2 months now. Pool has been clear and trouble free the entire time. Have only had to add about 16 oz of bleach a day and about 8 oz. of MA a day. All chemicals have been in range (usually). Right now everything is "perfect" except FC at 2.5. CC = 0, CYA = 45-50, pH = 7.6-7.7, TA = 90

    I noticed today green growing on the white plastic ports. Should I just bring FC back up to 5, or should I shock to 20?
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    Mod Squad jblizzle's Avatar
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    Re: Shock or not to shock?

    If you see algae, then the shock process it's usually a good idea.

    Did the FC drop a few times ? Or maybe the circulation is bad where the algae is showing up?

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    Re: Shock or not to shock?

    If I saw green in my pool I would raise it up to shock level and do an overnight test just to be safe. I keep my CYA at about 55 and don't like to see my FC drop below 4ppm.
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    tcat's Avatar
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    Re: Shock or not to shock?

    I'll shock. I brought it to 5.0 because I don't have enough bleach right now. Drops about 1.0 each night, I may have missed adding Clorox yesterday, so it got below 4.0. I'll do a search for the overnight test.
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    Richard320's Avatar
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    Re: Shock or not to shock?

    Don't forget to brush that green away. Algae can grow a slime coat, sort of like a scab, that needs to be brushed away so the bleach can penetrate and kill it.
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    tcat's Avatar
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    Re: Shock or not to shock?

    Just brushed, looks like I need a new brush... all kinds of white hairy things floating now. Any "best" recommended brands/types?

    Will check FC in about an hour, hopefully two 182 oz will be enough (what PC said to add). You're supposed to keep it at 20 until it goes down less than 1 overnight? That seems odd if you want it back to 5. Do you just quit adding until it hits 5? (like 15 days)?
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    Re: Shock or not to shock?

    FC will usually deplete by half on a nice sunny day, sometimes more, sometimes less. The higher your FC concentration, the higher the burn rate.
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    Re: Shock or not to shock?

    Any brush will do... I think they are almost all the same no matter where you get them. I would check prices in the area for the best deal. I was going to suggest you might find a sale being it's the end of the season for many... but I see now you're in Texas, so not likely.
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    tcat's Avatar
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    Re: Shock or not to shock?

    All is well... with CYA of 45 I shocked to 18 yesterday, waited 3 hours and was at 17, so I left it there. 12 hours later (7:30 AM) it was at 16. 10 hrs later (now) it's at 14.5. 100 degrees yesterday and today. pH was high this AM, so I added 32 oz. MA to bring it to 7.6. Crystal clear, no signs of growth. I'll make sure FC doesn't go below 4. Thinking of adding a few pounds of borates.
    IG pebble, 15,000 gallon
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    tcat's Avatar
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    Re: Shock or not to shock?

    FC levels from 18 shock, 24 hour intervals: (84 degree pool, 100 degree days, mostly shade)

    18-14.5-12.5-11-10-8.5-7.5

    Will be 1 week tomorrow and haven't had to add a drop of Clorox! Should be close to the CYA high end by tomorrow. Trying to decide whether a "Liquidator" is worth the money. Can buy about 70 jugs of Clorox for the cost of the unit (2-3 years worth!)... I'm lazy, but it seems the time messing with the machine and potential leaks, may not justify the 5 minutes per day adding a qt. of Clorox.

    Adding Borates this weekend (if my test strips come in)... I figure it's probably a good idea to test 1st before starting to add (since I recently moved in and have no clue what may be in the water).
    IG pebble, 15,000 gallon
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    Re: Shock or not to shock?

    Tcat,

    If I have understood your posts correctly, it sounds like you have brought your pool up to shock level, tested to make sure it was there and just let it slowly drop on it's own.
    You need to be sure and pass the three criteria as follows; passing an OCLT of less than 1PPM, CC less than 0.5 (which it looks like you are OK here, but this can go up while shocking), and that your water is clear.
    All while keeping FC at shock level until you pass the above 3 criteria.

    From what you have posted, it doesn't look like you have maintained your FC shock level consistently until you have met all 3 of the above criteria, which are outlined in pool school.

    I'd just hate for you to see it come back after you have done all the work of starting it.
    It sounds like you have started out correctly, just keep up with the FC, hang in there, read up on the shock process and keep on it, you'll be rewarded in the end.

    Also, you can't reliably read pH above an FC level of 10ppm, so just set your pH target to 7.0/7.2 at the start and then just leave it alone until you're done.

    Lastly, you did say in your 1st post that you add M.A. daily, why is that? Does your pH keep drifting upwards?

    Remember, the MOST IMPORTANT THING is to just keep adding bleach and keep your FC levels up slightly above shock level, never letting it dip below. JUST IGNORE the other things until the shocking process is complete and all criteria have been met. Then you can adjust them at that point.
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    tcat's Avatar
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    Re: Shock or not to shock?

    Thanks for the great response. I just wasn't sure about how long to maintain the shock level. It was 18, drifted to 17. I didn't know I should have brought it back to 18. Since it didn't drop more than 1 overnight, I assumed I was OK. CC=0 all week. I "thought" I passed all 3 tests.

    Yes, my pH seems to drift up. Either that or is was way above 8.2 and I just kept adding daily until it finally looked like 7.6.

    From what I've read, FC dropping 2.0 per day is about normal? Mine drops between 1 and 2 (closer to 1). My pool has stayed very clear through the whole process. I only shocked because I saw some green on the white plastic fittings. I brushed and nothing was coming off walls.
    IG pebble, 15,000 gallon
    48” PentAir DE Filter with backwash valve
    PentAir Whisperflo pump with 1hp 2-speed motor
    Aquabot 4WD, Poolskim
    Intermatic Dual Timeclock with freezeguard
    DIY chlorine feed
    BBB

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