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Thread: Newbie - Lost all Chlorine and CYA - Help appreciated!

  1. Back To Top    #1

    Join Date
    Jun 2015
    Valley Center, KS

    Newbie - Lost all Chlorine and CYA - Help appreciated!

    Need a little help here. First season operating a pool. All seemed to be going well until this week. I have been testing regularly (TF100 kit) and have had some issues maintaining a consistent chlorine level, but have been in range for the most part. Earlier this week the pool started to cloud up a bit and I had not shocked it for a while so last night I dumped in 3 lbs of lithium based shock. It was late and I did not get a chlorine reading after the shock, nor did I this morning (an obvious oversight/mistake).

    I just tested the water after work and below are the reading I have. I was completely surprised to see a big fat 0 chlorine. The even more surprising part is that in the last 5 days my CYA has gone from a solid 30 to below 20. I run trichloro tabs as this was a new fill this year and decided to use those to elevate my CYA levels and provide consistent chlorine until everything stabilized. Not sure if that is the right logic, but that is how I tackled it.

    I did look today and the tablets in the chlorinator are pretty much dissolved so I filled it back up and added an extra in the skimmer to start boosting chlorine and CYA.

    I am open to advice here.....why would my chlorine be 0 with a chlorinator and after shocking last night? Also why would I have lost CYA? It has been hot and sunny here 95+ for the past week or so, so I expected to lose chlorine but not CYA.

    My plan now is to shock it again tonight with at least another 3 lbs (21000 gal pool) and hope the CYA rises with the fresh stack of 8 tablets in the chlorinator. However as I said I am new to this and need advice. I want to get the pool in tip top shape before the 4th weekend when we will have folks using it a lot.

    Help please! Below are the reading as of this evening after shocking last night..... Thank you - Ryan

    FC - 0
    CC - 0
    CH - 300
    TA - 250
    PH - 7.5
    24,000 gal IG 16x36 rectangular
    20 Mil Merlin Vinyl Liner (new 2015)
    1 HP Hayward SP2607x10 Pump (42 gpm)
    Hayward Sand Filter
    Well Water Filled (high Iron content)

  2. Back To Top    #2
    Mod Squad pooldv's Avatar
    Join Date
    Aug 2012
    DFW, TX

    Re: Newbie - Lost all Chlorine and CYA - Help appreciated!

    You probably aren't getting CYA into the pool fast enough to combat the FC loss from the sun. Sun is eating up the chlorine faster than it is dissolving.

    Chlorine level is set based on CYA level and the Chlorine CYA Chart. If chlorine drops below minimum then the pool is not sanitized and algae will grow.

    Once the pools spends some time with chlorine below minimum and starts to cloud up you will need to Pool School - SLAM - Shock Level And Maintain to clear the algae. Add 30ppm CYA granules and use bleach to get the FC up quickly.
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