Industry moving toward CYA at or below 50 ppm

needsajet

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I started a survey regarding liquid chlorine dosing, and hopefully something will come out from it. If there's anyone watching this thread who also has liquid dosing, please help kick it off, thanks. SURVEY - Liquid FC Dosing

I don't mean to be argumentative for the sake of it, Matt, but I do lean strongly toward evidence. I was looking for prior threads on chlorine dosing and bumped into a survey regarding SWC run times and percentage settings. There were 17 responses and none of them were running their SWCs at 100%, so it seems illogical to me that SWCs are driving pump run time. There was a wide range of pool volumes covered.

For these 17 respondents, the average SWG run time was 40% with 2/3 of them running at 20% to 60%. So all 17 could easily reduce pump run time by turning up their chlorinators. Clearly they are determining pump run time for other needs, or at least some of them would increase the SWG % and run the pump for fewer hours. Longer run time might be partly due to a desire to dose chlorine across daytime bather load and UV extinction, or it could be to keep the water features, slides or solar heating running. I think as often as not, it's to keep the pool well-skimmed and looking great. As I mentioned previously, I've certainly seen cases here involving over-sized single-speed pumps and under-sized SWCs where pump run time has been increased for the SWG. But that seems to be the exception, not the rule. We almost never hear of people running their SWG at 100%, so it appears that the vast majority of pool owners are extending pump run time well beyond any need defined by the SWC. Most competent pool owners here at TFP talk about 25% to 60% SWG settings, so I think this relatively small set of data is pretty darn close to representing the norm.

In my case, for days without swimming, I've played with it a bit and 5 or 6 hours of filtration on low speed keeps the pool sparkly. That's also enough to add 3 to 4 ppm FC if I needed to. But I choose to run the pump for 10 or 11 hours so it covers the full time there is sun on the pool, higher likelihood of bather load to be absorbed, and bugs landing in the pool along with leaves that need to be skimmed. Day time operation, I think, allows for quickest removal of bugs and leaves, along with slow and steady chlorination at the time it's needed the most, be it for bather load or UV extinction. For me, skimming seems to be the dominating factor.
 

AUSpool

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We're getting a bit off track here but I've got 2 pools and both are now below minimum pump run time because of too much FC. A 15,000L at 2hours with the SWG at 20% and a 30,000L at 1.5hours with the SWG at 50%. - winter. It would be nice to be able to run the pump/filter independant of the SWG. In summer I never run the pumps more than 4 hours. I found that the variable speed pump doesn't skim very well on low, even on medium it's not as good as I could be. My run times are based arround solar PV gain or payback. Most shops and pool service guys around hear will say to run a pump for at least 8hours a day, the pump is making their job easy and their not paying for the power. I had always thought pump run times were making up for poor pool management and knew I was onto something when I read Mark's link.
 

Lykly

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Depending on who does the test, I get 60 to 65 CYA, the pool store says 50, but I'm leaving well enough alone. It's probably because I have a way bigger SWG then I need, but I only run it a little better than 30% power for eight hours a day and it does a very good job maintaining chlorine. I don't intend on changing anything. I should add, when I test for CYA, I go until I absolutely see no sign of that dot. I try to keep my chlorine at 5, it varies one half ppm.


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JoyfulNoise

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Great survey. Only thing is, I would have collected a little more data on actual FC and CYA targets as well as any changes during season (summer versus winter, etc. )

As for the SWG data, interesting as well but 17 respondents is a fairly small sample size. One also needs to consider the role of automation as well. I have a fancy automation panel that allows me to setup various pumping scheduled with and without the SWG. I can do this all at the push of a few buttons. Not everyone has that level of control and so it will change their behavior with pump run times.

Maybe you should start a new SWG survey? Id be happy to submit my information.
 

JoyfulNoise

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Is Richard (chemgeek) still around?

Kind of off-topic, no??

Yes, Richard is still around but he's not really posting on TFP anymore. You are welcome to e-mail him at his external e-mail address if you have a question for him.
 
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