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Thread: How much FC is lost per day?

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    How much FC is lost per day?

    OMG - I feel like I keep reading the same stuff over and over but only picking up a small bit each time (and its always the "ohhhh" factor when it finally clicks). I am a new pool owner (2 wks old). I would think that if a pool builder or store would be honest about chemicals and chemistry that they'd get more business because they'd earn the trust of the community. Maybe that's inaccurate, perhaps they can't survive on bleach sales alone.

    Anyhow - I've used pucks for about a week and will be switching over to the bleach method today. The problem is that I don't know how much FC I'm losing per day so I don't know exactly how much bleach to put in per day. Is there a baseline that I can use to judge with and then just keep testing? I hate to put way too little or much in if I can just learn from your experience.

    My pool is 14,000 gallons, 375 sq ft, in DFW with full sun and high temps ranging from 95-100*. The pump is on roughly 10 hrs per day. I lose about 1.5-2 inches of water due to evaporation each week.

    My water analysis from yesterday reads like this (which tells me I probably want to maintain FC at 5 or 6, is that right?):

    FC 3.06 (pool store said this was perfect but I think I need to raise this to 5 or 6, right)
    TC 3.25
    CC .19
    pH 8.1 (I added half a gallon of muratic acid this morning)
    CH 314
    TA 114
    CYA 54

    Thank you in advance for your help.
    New Pool: 22 x 35 | StoneScape Mini - Midnight Blue | ~17,500 gallons | Jandy Equipment - Built spring 2015 (click for details and pictures)
    Old Pool: 16 x 30 | QuartzBrite | 14,000 gallons | Pentair Equipment - Built summer of 2013 (click for details and pictures)

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    Richard320's Avatar
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    Re: How much FC is lost per day?

    Welcome!

    First, if you want to take control of your pool, you need your own test kit. Period. Chlorine consumption can vary hugely, depending on temperature, how many people use it, CYA levels, and how much sun it gets, amongst other variables. Figure 2-3 ppm per day. If you plug your pool size into http://www.poolcalculator.com/ and plug zero and three into the FC box, it will tell you how much bleach, depending on concentration, that works out to in your pool.

    You need your own test kit. Period. It's the single best investment you will ever make in your pool. If you just dump X amount of bleach in every day and trust the pool store (bad idea) to test it once a week, what happens if there is an algae bloom and the residual FC drops to zero? You won't know until too late. Although you will be conveniently there at the store where they will load you up with various shocks, clarifiers, and algaecides, all likely to cost more than twice the price of a TF!00 test kit.
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    Re: How much FC is lost per day?

    I did buy one of those TIF tests. I have been (and will continue) to test daily. Its been nice having the pool store "verify" my numbers. They're usually very close which gives me a little confidence.

    I was just hoping not to wing-it at first but I did plug all my figures in to the pool calc. That thing is all kinds of useful! I'll presume 2-3 ppm and go from there. Thank you very much.
    New Pool: 22 x 35 | StoneScape Mini - Midnight Blue | ~17,500 gallons | Jandy Equipment - Built spring 2015 (click for details and pictures)
    Old Pool: 16 x 30 | QuartzBrite | 14,000 gallons | Pentair Equipment - Built summer of 2013 (click for details and pictures)

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    Mod Squad jblizzle's Avatar
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    Re: How much FC is lost per day?

    Post up a set of YOUR test results as they are more trusted, especially the CYA number which the pool stores are bad at and it determines what FC levels you should be maintaining.
    Jason, TFP Moderator
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    Butterfly's Avatar
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    Re: How much FC is lost per day?

    If your CYA is about 55, then you should keep FC between 4 and 9, and never below 4.

    Test FC each evening and add enough bleach/liquid chlorine to reach 8 or 9.

    Test and add the next evening, about the same time. You should be able to get a good handle on knowing how much FC your pool loses daily.
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    Re: How much FC is lost per day?

    If you are just looking for an order-of-magnitude, you'll probably need to add 2-3 ppm FC per day. It could be a little less if you have less sunlight on your pool and it could be more (say 4 ppm) if you've got a lot of sunlight on the pool and perhaps some catch-up to do oxidizing organics in the pool or in your filter.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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