Holy Chlorine, Batman!!

Hi, Folks,

I'm not sure if there is anything to be learned from this but just had to post it. A coworker asked me to test his pool water. He had relied heavily on an inline chlorinator and pucks to keep his water clear for years. He suspected he had a problem cause his test strips gave no reading and he asked me to test a sample for him with Ben's kit. Here's what I got

FC - 44
TC - (what's the point?)
pH - 6.8 - 6.9
Alk - 80
CYA - 120 plus

I told him that if he didn't like the color and pattern of the liner not to worry 'cause it would be gone when he got home!!:D

Amazingly, 10 days later of adding nothing and his FC is down to 22 and his liner DID NOT fade one bit. I'm assuming the buffering of the CYA protected him....I can think of no other reason he has any color at all in his liner.

Again, I doubt this has any value to anyone, but I simply had to post that FC - 44 :) :)

Yikes. What was he thinking?

Jeeez. That's pretty high. I bet he's going to need a TON of borax to get his pH up. I'm sure it's below 6.8. It's gotta be if he burned enough tabs to get to 44 ppm Cl

Michael

Michael,

I forgot to add that that his pH was 7.2 the second time I tested for him (10 days after the 44 - FC.) I have no idea how that was possible. :)

Wow!! At a CYA or 120+, he would need to be at 25 PPM to shock the pool....44 is crazy. What about his hair and swimsuit....did he notice anything bleaching??

Quote:

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Originally Posted by duraleigh

Here's what I got

FC - 44
TC - (what's the point?)
pH - 6.8 - 6.9
Alk - 80
CYA - 120 plus
...

Amazingly, 10 days later of adding nothing and his FC is down to 22 and his liner DID NOT fade one bit. I'm assuming the buffering of the CYA protected him....I can think of no other reason he has any color at all in his liner.

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Actually, such posts have quite a bit of value, at least to me. They provide me with external confirmation of some of the points I've made here. For example, I assume he'd been swimming in the pool with no observed ill effects? That's what I'd expect, but it's totally contrary to what's found in all the literature.

Ben
"PoolDoc"

Quote:

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Originally Posted by vanhout

Yikes. What was he thinking?

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With most test methods, there's no way to determine 44 ppm. OTO will be dark orange at that level; DPD tabs will be clear. So, he may have thought his chlorine was too LOW!

Quote:

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Originally Posted by duraleigh

I forgot to add that that his pH was 7.2 the second time I tested for him (10 days after the 44 - FC.) I have no idea how that was possible.

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The Taylor reagents are stabilized against chlorine, but not to 44 ppm. As far as I know, the only reliable method of testing pH, when the chlorine is that high, is a RECENTLY CALIBRATED pH meter.

Ben
"PoolDoc"

Hi, Ben,

No swimming yet. We're in Raleigh, NC, and while my pool is temporarily drained, I suspect most pool temps to be in the 60's.

He's a mercenary sort of guy......maybe we could all chip in and get him to take a dip.....see if he turns into an albino!! KIDDING! KIDDING! KIDDING!:D

Yesterday (10 days after the 44 FC) was when I got the 7.2 pH and 22ppm Cl.

Actually, one good result. After seeing Ben's kit, I'm pretty sure he is a convert and will be ordering the PS234 in the very near future

How could his pH go up? Is his pool open? Is the filter running? Then let's not forget our T/A lowering procedure....

"...then when the pH is below 7.2, aerate your water to raise pH..."

So his water is aerating and raising the pH.

Of course, this assumes that the 7.2 is vaguely accurate given Ben's caveats.

FYI....I just changed my 9 year old liner DIY...18X36 sport pool, 20k gallons, filling back up right now.

When the pool was installed in late fall, they added EIGHT gallons of 12% pool bleach. No pump to circulate, they left everything winterized. Told me to add EIGHT gallons again in the spring. After the spring, I learned not to do that again but also didn't notice any sudden fading. But over time....it certainly did, almost all the color was gone from the bottom despite being very conservative relative to shocking and chlorine levels.

But that's not all. After draining the pool I had my box cutter ready to section it for removal. Came in handy for the sides as they were still pliable, but the bottom? My index finger cut right through it turning it to glass like shards. More like thin plastic than vinyl. Popped and snapped any where I touched it. Had we not changed it this year somebody's foot would have gone right through it along the coves where it pulled back.

Just an FYI...sometimes the evidence of over chlorination shows up later...Tony

Quote:

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Originally Posted by PoolDoc

The Taylor reagents are stabilized against chlorine, but not to 44 ppm. As far as I know, the only reliable method of testing pH, when the chlorine is that high, is a RECENTLY CALIBRATED pH meter.

Ben
"PoolDoc"

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DITTO THAT, Ben! At that high a chlorine level just about all the phenol red would probably have converted to chlorphenol red which is yellow at a pH of about 5.0 and turns purple at a pH of about 6.6 with shades of orange, red and red-purple in between, similar to phenol red from ph 6.8-8.2. So, if the pH appeared to be about 6.8 (yellow orange with phenol red test block) it was probably MUCH closer to about 5.2!!!!!!!!!!!!!!!!!!!!!!!!!!!) Trichlor is VERY effective at lowering pH, as we all know too well ;)
Once the chlorine level started to drop to 22 ppm then the sodium thiosulfate in the pH indicator might actually have had a chance to kill some of the chlorine and less of the phenol red would convert. Hence the apparent jump in pH. I would have to guess the pH was STILL probably at or below 6.0 however. The indicator color would be a mixture of both the phenol red and the chlorphenol red in some unknown proportion at this point so the pH reading is still probably bogus.

This may be worth nothing also, but what this gent experienced does not surprise me....


If one relies soley upon what pool stores are telling clients, and if one does not know first hand the basic chemistry involved (thank goodness I found this site and forum!), one could easily end up in this siuation not knowing what the problem is.

I recently went to a 'pool school' sponsored by a reputable pool compnany here in town. The seminar was given by a salesman for one of the leading pool chemical companies.

I was astonished at what the guy was telling the group as 'facts'. He was advocating the sole use of their sanitizer sticks to maintain chlorine levels in the pool. I asked what would happen to stabilizer levels if one followed that practice. I was told outright that 'scientific tests performed by their company have confirmed that stabilizer levels have no effect on the ability of chlorine to sanitize, and that the levels can increase to very high levels (several hundred ppm) with no consequence on the efficiency of chlorine". He reassured the group that one could use their sticks for many years before pool water would have to be replaced to reduce stabilizer. Top that with the fact that he never warned about having to increase chlorine levels to 'achieve' efficiency as stiabilizer builds up, and that the usual test strips and kits can give false readings of chlorine at levels above 10-15 ppm due to bleaching.......Im sure a large number of those naive pool owners are going to exericene this same problem...