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High Free Chlorine


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#1 Alan

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Posted 09 June 2007 - 03:17 PM

Our pool has been running a high free chlorine level for 3 days now at about 10. Ph is at 7.4, TA is 180. We've had 3 days of sunshine, shouldn't Free Chlorine be dropping by now? I have a little girl chomping at the bit to go swimming. Is my best option to wait it out? Any advice is appreciated were new pool owners.

#2 waterbear

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Posted 09 June 2007 - 08:47 PM

How high is high? if the FC is below 10 ppm and there is not CC then you can swim. Also how high is your cyanuric acid. If the levels are high then the chlorine will not burn off quickly in sunlight (and if they are too high your chlorine is also not an effective sanitizer anymore!)
Please post a full set of test results so we can tell exactly what is going on in your pool!
I've tested more water than I ever care to think about!
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#3 Alan

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Posted 10 June 2007 - 04:58 AM

Thanks for help. Total hardness 500, Total chlorine is 5, Free chlorine is 5, Ph is 7.4, Total alkalinity is 180, cyanuric acid is 30-50. Were improving I guess, FC was at 10 for 3 days.

#4 waterbear

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Posted 10 June 2007 - 07:39 AM

A bit of advice. Stop using test strips. They are ok for a quick daily check on chlorine levels but are pretty useless for anything else. Total hardness is not really very valuable for a pool and all strips test total hardness. You are interested in calcium hardness. CYA tests on strips are just not reliable. Get a good test kit , preferably with the FAS-DPD test for chlorine and not the DPD test. (I recommend the Taylor K-2006). You won't regret it!
I've tested more water than I ever care to think about!
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#5 Jerry Materne

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Posted 15 June 2007 - 12:47 PM

uh, correct me if I'm wrong but doesn't the warnings on your chlorine containers tell you not to swim in the pool until the FC drops below 3ppm??? Where in the hell are you getting off saying 10ppm is swimable. Don't invite me to any of your pool parties buddy. Quit blowing mony on expensive test kits. You'd be better off taking a class on reading comprehension.

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#6 waterbear

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Posted 15 June 2007 - 01:06 PM

QUOTE(Jerry Materne @ Jun 15 2007, 04:47 PM)  
uh, correct me if I'm wrong but doesn't the warnings on your chlorine containers tell you not to swim in the pool until the FC drops below 3ppm??? Where in the hell are you getting off saying 10ppm is swimable. Don't invite me to any of your pool parties buddy. Quit blowing mony on expensive test kits. You'd be better off taking a class on reading comprehension.

Jerry Materne

Check out a new edition of the CPO handbook for accepted levels. You'll find the info there. Many state health departments are now setting 10 ppm as the level that bathers can enter a commercial pool and it's been generally accepted in chlorine sanitized spas for a while. Also, new studies in CT times have shown that 1 ppm FC, even in an unstabilized pool is not high enough to kill many pathgens and generally accepted minimum levels are now 2 ppm and higher. Perhaps you might want to start reading some of the newer info that has been published.
I've tested more water than I ever care to think about!
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#7 Jerry Materne

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Posted 15 June 2007 - 03:00 PM

Rubbish..........3ppm has been set as the absolute maximum the human skin can tolerate without getting irritated. When the chlorine manufactures revise it I'll consider it. Hell, if the new safe max is 10 ppm I'm suprised the chlorine makes didn't put that crap in their instructions. After all, that would require you to make more of your product...............I doubt your source and you really shouldn't be posting these "new norms" until they're universally accepted.

Bake in your own pool dude.......I'll stick to the old method.

Oh, commercial pools see more use, maybe that is why they suggest higher levels........if I'm right, most public commercial pools limit your time in them and since the bather load is so extreme I'm pretty sure they're counting on that 10ppm to not stay high long...

#8 waterbear

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Posted 15 June 2007 - 03:15 PM

QUOTE(Jerry Materne @ Jun 15 2007, 07:00 PM)  
Rubbish..........3ppm has been set as the absolute maximum the human skin can tolerate without getting irritated. When the chlorine manufactures revise it I'll consider it. Hell, if the new safe max is 10 ppm I'm suprised the chlorine makes didn't put that crap in their instructions. After all, that would require you to make more of your product...............I doubt your source and you really shouldn't be posting these "new norms" until they're universally accepted.

Bake in your own pool dude.......I'll stick to the old method.

Oh, commercial pools see more use, maybe that is why they suggest higher levels........if I'm right, most public commercial pools limit your time in them and since the bather load is so extreme I'm pretty sure they're counting on that 10ppm to not stay high long...

The "new norms" are accepted. You obviously don't know a lot about pool chemistry. Where did you ever get that 3 ppm is the abosulte maximum the human skin can tolerate without getting irritated? You obviously also don't know what a CPO handbook is either.

Perhaps you should learn a bit before you post. (And FYI, I am not just a pool owner. I am in the industry.)
I've tested more water than I ever care to think about!
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#9 Jerry Materne

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Posted 15 June 2007 - 04:03 PM

Dude, you're a <deleted>.............10 ppm is not recommended or suggested by the CDC for safe pool water. I don't care what the CPO says........it obvioulsy doesn't have anyone from the health field advising whoever is writting it. I'll take the word of a doctor over the word of the EPA or a Pool Tech any day.

#10 waterbear

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Posted 15 June 2007 - 04:11 PM

QUOTE(Jerry Materne @ Jun 15 2007, 08:03 PM)  
Dude, you're a <deleted>.............10 ppm is not recommended or suggested by the CDC for safe pool water. I don't care what the CPO says........it obvioulsy doesn't have anyone from the health field advising whoever is writting it. I'll take the word of a doctor over the word of the EPA or a Pool Tech any day.

The CDC does not set standards for safe levels of chlorine, only for disinfection regimes to follow in case of fecal accidents, which have to do with ct vaules (kill times) for such parasites as crytosporidium. On their website they differ to state Health departments for recommended levels for normal sanitation. The EPA is who has jurisdiction over swimming pool and spa sanitizers in the US. I suggest you do a bit of further study and get your facts straight!
I've tested more water than I ever care to think about!
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#11 itabb

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Posted 15 June 2007 - 06:02 PM

I can't tell the difference in the water between 10ppm and 2ppm, as long as there's no chloramines. I suspect at a CYA level of 50-80, 1 or 2ppm would be pretty ineffective at keeping my family safe. I like to operate around 4-6ppm. Keeps the water looking really crisp and feeling clean. Then again, I am from Pinellas County, Florida, where the tap water's TC is around 4-6ppm, and I've never had a problem drinking that. Crazy, eh . . . had the water inspecter out to my house, he said it is safe to drink. /shrug
Location: Atlanta, Georgia.
Pool: 15,000 gallon 18'x36', 3'-6' deep in-ground gunite pool, Sta-Rite 3 125 GPM 2-filter cartrige, 1.5 HP Sta-Rite pump, solar heater, Goldline SWG, Jandy controls, opaque automatic solar pool cover, 3 waterfalls (not from spa).
Spa: 485 gallon in-ground square acrylic over fiberglass suspended over gunite Sunset brand spa, isolated system, natural gas heater, 2-speed (4hp/11hp) main pump, 3hp booster pump, chlorine sanitized.

To my pool store owner, nothing is more important than my pool and my money.

#12 chem geek

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Posted 16 June 2007 - 03:21 AM

Jerry,

Your comments regarding maximum chlorine levels are appropriate for water that does not contain any CYA in it or for water that is consumed by drinking it (i.e. tap water). It does not apply for pools that use CYA since it is the disinfecting chlorine (hypochlorous acid) level that is the disinfectant, inhibits and kills algae, and is the oxidizer that damages skin, etc. See this link for more technical info on the CYA/chlorine relationship including a spreadsheet that calculates the disinfecting chlorine level. Essentially CYA combines with most of the chlorine to form what are called chlorinated isocyanurates and these are not effective sanitizers nor prevent algae nor irritate the skin. They can be best seen as a chlorine "buffer" since they release chlorine as hypochlorous acid as it gets used up (i.e. it's an equilibrium with a relatively fast half-life of 0.25 to 4 seconds -- i.e. half of the buffer can be released to chlorine in seconds).

The common standards for pools do not take into account the combination of CYA and chlorine levels and that is wrong. By trying to oversimplify by just setting ranges for each parameter separately, pools with high CYA (around 100) and recommended FC levels of 2-3 ppm can get algae and there are numerous reports of this on multiple pool forums. Maintaining higher FC levels at higher CYA levels as shown in this chart prevents algae (at a minimum of the "0.03" column for disinfecting chlorine level for manually dosed pools -- SWG pools seem to be able to get away with the "0.02" column most of the time). Obviously one shouldn't follow the chart for low CYA levels since one still needs a buffer of chlorine in the pool as it gets used up locally, so a minimum of 2 ppm FC regardless of the chart value is appropriate (unless alternative systems are used to handle some of the chlorine demand, mostly from oxidizing organics, and to inhibit algae so metal systems or ozonators, etc.).

Spas are a different animal due the bacteria that causes hot tub itch that requires higher disinfecting chlorine levels to kill, but I've talked about that in other posts on this forum. This post is an early one on this forum that talks about this including some other references to the CYA/chlorine relationship. I started getting involved with this about 2 years ago when I had problems with my own pool when the CYA levels went way up due to using Trichlor tablets and having a cartridge filter (so no backwashing).

My wife uses a local indoor pool during the winter and that pool has around 2-3 ppm FC with no CYA. Her swimsuits degrade over a single season and her hair dries out considerably. During the summer (actually, around 7 months) in our own outdoor pool with 3 ppm FC and 20-30 ppm CYA she experiences no degradation of swimsuits and her hair does not dry out (in both winter and summer she does take a shower to at least rinse off after swimming). The difference is that the indoor pool has over 30 times as much disinfecting chlorine since it has no CYA which means the chlorine reacts to oxidize organics in rubber and dye in swimsuits 30 times faster as well as proteins and other organics in hair.

Richard

#13 Alan

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Posted 16 June 2007 - 06:38 AM

WOW! I didn't mean to cause such a controversy. Granted I'm a Newbie and just trying to understand basic water pool maintenance. Waterbear, sorry you had to get into such an arguement with such a "know it all". Thankfully my comrehensive skills are good enough to see he is low class and thats OK, Live and let live is my motto. Its clear to me as a newbie waterbear and chemgeek have the experience and know how and I thank you for your help.




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