Red eyes!?!?

Arstechnica

Member
Jul 30, 2010
14
Okay I can't figure out what is causing this but here are my values:
FC 5
TC 3
PH 7.6
Alk 90
Salt 3900
Borate 30-50
CYA 80
CH 350

Me and the kids get red irritated eyes after 1 hr of swimming. Is this normal or is there a value that I am forgetting?

Thanks in advance!
 

zea3

Mod Squad
TFP Expert
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Jul 10, 2009
11,094
Houston, Texas
Total chlorine (TC) cannot be less than free chlorine (FC). The equation for TC is FC+CC=TC. The CC is Combined Chlorine, the "waste" chlorine that needs to be shocked to get rid of it. If your TC is actually 5 and your FC is 3 then you have a CC of 2. When you have CC greater than .5 then you need to shock your pool. High CCs can cause eye irritation which is probably what is going on with you and the kids.
 

Arstechnica

Member
Jul 30, 2010
14
Nope, FC is 5 and TC test was 3, the only way to get CC in my kit is to subtract TC from FC to get CC. I know it os a negative value, can someone comment on this?
 

dmanb2b

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Apr 4, 2009
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NY
Arstechnica said:
Nope, FC is 5 and TC test was 3, the only way to get CC in my kit is to subtract TC from FC to get CC. I know it os a negative value, can someone comment on this?
I'll comment...you are doing something wrong. CC can not be less than zero and TC = FC+CC
 

Arstechnica

Member
Jul 30, 2010
14
Well that is what I am getting. My test kit is a Taylor k 2005. The test does FC, then you measure TC. The only way to get CC is to do TC - FC to get CC. If TC is negative, does that mean I have a high CC?
 

JasonLion

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TC is not negative, can never be negative. You are doing something wrong.

One likely problem with the DPD chlorine test in the K-2005 happens when either the FC or TC level is above 5. That can cause the test to read falsely low (even read zero when FC/TC is actually very high). Try doing the test again with dilution, ie mix one part of pool water with an equal amount of chlorine free water (typically distilled water), test that, and multiply the result by two. That will make it less likely that you go over the limit and get false readings.
 

JasonLion

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Normal chlorine levels used in swimming pools will not cause any eye irritation. In this context normal is between the minimum and shock level for your CYA level. With CYA around 80, your minimum is around 6 (or 4 if you have a SWG).

Chlorine causes eye irritation at far higher levels. Straight bleach would cause a dramatic amount of eye irritation. But at the levels typically used in swimming pools it is not even detectable.

I suspect that either your FC level is too low (5 instead of 6) or you have a substantial CC level. But it is difficult to tell without knowing your test results with dilution.
 

Arstechnica

Member
Jul 30, 2010
14
Okay I did the dilution method and the CC is infact 0. My chlorine is at 4-5ppm, pH 7.4, alk 80, cya 80, borate 50. Now I could just be picky, but I would think that if my levels are like this, I should feel no irritation or reddness what so ever. What do you guys think? It could just be me expecting too much from near perfect readings?

Thanks again!
 

JasonLion

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Your readings are not perfect. As mentioned previously, your FC level is too low for your CYA level (unless you have a SWG that you haven't mentioned). With CYA at 80, FC should be between 6 and 11, and never below 6.
 

dfenrick

LifeTime Supporter
Jul 13, 2010
23
SE Alberta, Canada
Is there a 'perfect' pH for comfy eyes? I would guess the the 7.4 - 7.6 reported should be pretty close to the pH of normal tears, but I haven't been able to find a definitive answer.
 

Ohm_Boy

TFP Expert
May 1, 2007
1,344
Orlando, FL
Do you have a salt water chlorine generator (SWG)? What other source of chlorine are you using?
I would suspect that if you have an SWG, you may be fighting a lurking algae bloom, and would need to shock to get rid of it.
 

chem geek

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Mar 28, 2007
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San Rafael, CA USA
dfenrick said:
Is there a 'perfect' pH for comfy eyes? I would guess the the 7.4 - 7.6 reported should be pretty close to the pH of normal tears, but I haven't been able to find a definitive answer.
The pH of human tears (actually, the fluids covering the human eye) varies but averages around 7.5 as reported in a paper I linked to in this post. However, another link in that post showed that pH wasn't a big factor in irritation, even in the range of 7 to 9, but low salt levels were irritating. Other links show that chloramines (such as those that show up as Combined Chlorine), especially nitrogen trichloride, can be very irritating.
 

geekgranny

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Aug 20, 2009
1,358
North Central Texas
chem geek said:
dfenrick said:
Is there a 'perfect' pH for comfy eyes? I would guess the the 7.4 - 7.6 reported should be pretty close to the pH of normal tears, but I haven't been able to find a definitive answer.
The pH of human tears (actually, the fluids covering the human eye) varies but averages around 7.5 as reported in a paper I linked to in this post. However, another link in that post showed that pH wasn't a big factor in irritation, even in the range of 7 to 9, but low salt levels were irritating. Other links show that chloramines (such as those that show up as Combined Chlorine), especially nitrogen trichloride, can be very irritating.
The pH in my pool, 7-7.2 doesn't bother my eyes nor my dog's eyes at all. As far as my skin and eyes I'm a very blond, very delicate flower. Just about everything irritates my skin and eyes but my pool water doesn't.

I've had spas for 24 years. I've used chlorine or bromine for sanitation since discovering TFP and keeping water balanced. I haven't had any eye irritation from spa water using BBB. When I used ionization and only non chlorine shock or used bromine and didn't know about proper balance I always had eye irritation and frequently had to use lots of other products to keep the water clear that made the irritation worse. For a year now my spa water has ranged from pH 7.0 to 7.8. As long as water is balanced and properly sanitized I have no irritation from that huge range of pH.

gg=alice
 

Arstechnica

Member
Jul 30, 2010
14
JasonLion said:
Your readings are not perfect. As mentioned previously, your FC level is too low for your CYA level (unless you have a SWG that you haven't mentioned). With CYA at 80, FC should be between 6 and 11, and never below 6.
I do have a SWG. Would the difference between the FC and CYA levels cause red eyes?
Thanks again!
 
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