The timing of FC minimum vs Target

Par4monkey

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Jul 11, 2020
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Assuming I understand that CYA levels determine your FC levels and that chlorine demand is influenced by sun, bather load, contaminants etc …..
If my minimum FC is 4 and my target is 6-8. So I use pool math in the evening to try to reach the 8? Then hope I don’t drop to 4 or lower during the course of the following day? And then if I know the next day will be hot or sunny and I’m hosting a party, so I try to get to 10 the night before and let it fall the next day?
For example, right now I’m at 5.4 (Taylor K2006). I can’t fall below 4. So Do I wait it out or add more chlorine at 5:15pm knowing the sun will still be out a couple of hours? I don’t think it’s realistic to check FC multiple times per day. Is this something I “journal” for awhile to see what my chlorine demand is and how much I lose on a hot sunny day and adjust the nightly dosage?
I’d love to hear how others have created a formula.
Thanks!5E1FF5C4-7ED8-4143-B328-38745382FC44.png
 
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Oly

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Jun 28, 2017
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First off do not focus on the minimum, rather focus on staying well inside or slightly above your target range. You are safe to swim above your target range all the way to your SLAM ppm. Now get too much above your target and you will see higher daily FC loss.
 

mknauss

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You are not sharing Poolmath logs so each time you ask a chemistry question, we pretty much need a full set of current test results to provide a reasonable answer.
 

Par4monkey

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Jul 11, 2020
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You are not sharing Poolmath logs so each time you ask a chemistry question, we pretty much need a full set of current test results to provide a reasonable answer.
Sorry, I didn’t realize I needed to post full results. I attached a screenshot. Just trying to figure out if people add chlorine throughout the day or shoot high at night and let it fall the next day.
 

Par4monkey

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Jul 11, 2020
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First off do not focus on the minimum, rather focus on staying well inside or slightly above your target range. You are safe to swim above your target range all the way to your SLAM ppm. Now get too much above your target and you will see higher daily FC loss.
Thank you for your explanation. I’m trying to figure out my FC loss throughout the day to determine a number I should aim for at night. Appreciate the e feedback!
 

Newdude

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Jun 16, 2019
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If my minimum FC is 4 and my target is 6-8. So I use pool math in the evening to try to reach the 8?
This is the issue with the minimalistic TFP approach. 99% of the time the goal is to do as little as possible and enjoy life as it’s not spent laboring over the pool. It is an amazing approach but this is the one crack in the armor.

You raise the FC to 8 in the evening and the following day you lose 4FC being peak season and you are dancing a razor thin line with your minimum….. AKA the # which you never want to touch. Or stand near. Or even THINK of. It is in fact the ‘minimum’ but that makes it seem OK when it is really something you want to avoid at all costs

If you target a 10 in this instance, and lose the 4 peak season FC, you are comfortably at a 6 and still in the target range. That buys you some leeway from extra swimmers, a freak storm or whatever else pops up while you are enjoying life because the pool is not preoccupying your time.

The season demand changes a good deal from start to finish like a bell curve. Month to month there may be a large difference, but day to day is unnoticeable. Tomorrow will for the most part be like today. You’ll get a feel for where you are and can dial your additions up/down as needed, but always steer way clear of that minimum.
 

JJ_Tex

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I am routinely above or at the high end of the target range. That way I will always be ready for the unexpected, be in life getting in the way or testing, animals leaving presents in your pool, gross kids, etc.
 

Par4monkey

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Jul 11, 2020
37
Pittsburgh, PA
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Vinyl
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This is the issue with the minimalistic TFP approach. 99% of the time the goal is to do as little as possible and enjoy life as it’s not spent laboring over the pool. It is an amazing approach but this is the one crack in the armor.

You raise the FC to 8 in the evening and the following day you lose 4FC being peak season and you are dancing a razor thin line with your minimum….. AKA the # which you never want to touch. Or stand near. Or even THINK of. It is in fact the ‘minimum’ but that makes it seem OK when it is really something you want to avoid at all costs

If you target a 10 in this instance, and lose the 4 peak season FC, you are comfortably at a 6 and still in the target range. That buys you some leeway from extra swimmers, a freak storm or whatever else pops up while you are enjoying life because the pool is not preoccupying your time.

The season demand changes a good deal from start to finish like a bell curve. Month to month there may be a large difference, but day to day is unnoticeable. Tomorrow will for the most part be like today. You’ll get a feel for where you are and can dial your additions up/down as needed, but always steer way clear of that minimum.
Awesome explanation! I’ll set my sites on 10 each evening! Agin, perfect way of explaining it !
 

Jenn1215

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Jul 6, 2018
45
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This is the issue with the minimalistic TFP approach. 99% of the time the goal is to do as little as possible and enjoy life as it’s not spent laboring over the pool. It is an amazing approach but this is the one crack in the armor.

You raise the FC to 8 in the evening and the following day you lose 4FC being peak season and you are dancing a razor thin line with your minimum….. AKA the # which you never want to touch. Or stand near. Or even THINK of. It is in fact the ‘minimum’ but that makes it seem OK when it is really something you want to avoid at all costs

If you target a 10 in this instance, and lose the 4 peak season FC, you are comfortably at a 6 and still in the target range. That buys you some leeway from extra swimmers, a freak storm or whatever else pops up while you are enjoying life because the pool is not preoccupying your time.

The season demand changes a good deal from start to finish like a bell curve. Month to month there may be a large difference, but day to day is unnoticeable. Tomorrow will for the most part be like today. You’ll get a feel for where you are and can dial your additions up/down as needed, but always steer way clear of that minimum.
So if my target max is 6, I should shoot for 9-10 at night so if it falls during the day I’m still within my range but not close to the bottom of 4. Makes sense. Thank you!
 
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Newdude

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TFP, which we all love is designed with the minimum in mind. Minimum cost, minimum effort, etc. you can always do *more* and still stick with the wonderful program.

Take brushing. We recommend once a week to free any bio films if present, whether or not you feel them. You can ABSOLUTELY brush 3X a week if your heart desires. It won’t hurt, can only help, and yet, you are still following TFP protocol by brushing your pool.
 
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Bperry

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Aug 20, 2020
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I always check in the morning while coffee is brewing. Then the levels are set for the day. Any benefit to checking at evening instead?
 

mknauss

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What is the schedule for the SWCG? If at all possible, it is best to test FC at the time it would most likely be at its lowest.
 

Bperry

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In my case it runs from about 10am to 8pm. So morning would be lowest FC unless there was FC usage during the day that consumed it enough to overcome the SWCG output.

Maybe manually chlorinating would be best done at night after the sun and bather load has consumed FC? Interesting and hadn’t thought of that.
 
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BowserB

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I'm no expert. I don't even play one on TV. However, remember UV varies by time of day, with astronomical noon being the worst. Here's a chart for June for Missouri (middle of America). There used to be a sunburn/skin cancer rule about avoiding summer sun from 9am to 3pm. The attached chart looks to be standard time rather than Daylight Saving Time, so you would shift 9-3 to be 10-4 for DST. Of course, where you are in your time zone would affect the precision of the chart, too. If you assume 8-5--normal work hours--as UV exposure time (for both the chlorine and people), you won't go wrong for the UV...organic matter additions are a different matter. I've been running my IC40 @ 20% 9am-8pm to address the sun and time people might be in the pool or spa; then again midnight to 4am, just to have some residual treatment, and in case it rains. That has been holding the FC at 6.5-7ppm with CC at -0- in spite of almost daily .5 inch or so rain showers. I get a deep water sample around 7am to test.

Incidentally, for health information regarding UV, here's a link: UVA vs. UVB Rays: What’s the Difference?
 

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