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Thread: Overnight CL loss test question

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    Join Date
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    Overnight CL loss test question

    When performing the overnight loss test, the pump should be left running right? Everyone says the only stupid question is the one not asked, but I feel stupid asking!

    Seeing as how I've been around here for a while now, seems like I'd know this by now...
    John

    24' round Vogue AGP 12,000 gal. Flotec AT251001-01 1HP pump, Hayward S310T2 sand filter, Aquarite SWG T-15
    TF-100 (found at TF Test Kits) with Speedstir and Samplesizer

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    JasonLion's Avatar
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    Re: Overnight CL loss test question

    It doesn't really matter if you run the pump the entire time or not, as long as you run the pump for an hour after the final chlorine addition and an hour before you test in the morning. If you are in the middle of shocking, then you should be running the pump 24x7 anyway because you are shocking. But it doesn't need to be running the whole time for the overnight test to be valid.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Overnight CL loss test question

    Thanks Jason. Man, it seems like every time I have a question, you're always right there to help out. Much appreciated!

    I'm not shocking (yet), we just finished filling the pool today and got the pump running. The water has a greenish hue, and I know we have iron in the fill water, so I want to rule out organics first. That way, I know exactly what I'm dealing with.

    I've added one bottle of sequestrant (added a little each day and mixed it manually) and it hasn't turned brown yet, so if it is the iron, hopefully one more bottle will take care of it.


    While I'm on the subject of iron (please move or split the topic if necessary), if the water has changed colors, the sequestrant will change it back, right? I know, another stupid question, but I don't think I've ever seen that actually said anywhere.
    John

    24' round Vogue AGP 12,000 gal. Flotec AT251001-01 1HP pump, Hayward S310T2 sand filter, Aquarite SWG T-15
    TF-100 (found at TF Test Kits) with Speedstir and Samplesizer

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    JasonLion's Avatar
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    Re: Overnight CL loss test question

    Yes, if the water has turned green or yellow because of metals in the water, sequestrant will turn it clear again. The only tricky part is that green water isn't usually caused by metals in the water. If the water starts clear and then turns a very clear transparent green right after you add chlorine, that it is going to be metals. But if it turns green at some other time or is cloudy/murky then it probably isn't related to metals.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Overnight CL loss test question

    Yes, this is clear transparent green, that became more and more obvious as the pool was filling. I was adding small amounts of bleach several times each day, because I knew it was going to take so long filling. At this point I'm not sure if it's the start of algae or the iron, but hopefully the overnight test will let me know what I'm dealing with.

    The pool was blue yesterday, although not sparkling, which made me think algae was beginning to take hold. Today, it was clear, (clear enough to see pretty much every speck of dirt in the pool standing on the ladder) and very very pale green, which make me think metals. So, I should know for sure tomorrow. After all, we know the overnight test doesn't lie!

    As of 10:20 tonight, my results are FC 7, CC >.5
    John

    24' round Vogue AGP 12,000 gal. Flotec AT251001-01 1HP pump, Hayward S310T2 sand filter, Aquarite SWG T-15
    TF-100 (found at TF Test Kits) with Speedstir and Samplesizer

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    Re: Overnight CL loss test question

    Okay, at 5:30 this morning, FC was 7, CC >.5 so at least I've ruled out algae.

    Also, my filter pressure has already risen 6 psi since I started it yesterday, so apparently it's filtering out something. The more iron it can catch though, the less sequestrant I have to use. Win/win for me, because I can get what seems to be a good seq. at about $6/bottle.
    John

    24' round Vogue AGP 12,000 gal. Flotec AT251001-01 1HP pump, Hayward S310T2 sand filter, Aquarite SWG T-15
    TF-100 (found at TF Test Kits) with Speedstir and Samplesizer

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