Question regarding CYA and FC

[dereksanders]

My wife has sensitivity to chlorine, hence the query. The level I’m maintaining is starting to take a toll. I’m aware that lowering FC level to barely above minimum is flirting with algae, but we have to do something.

Is the feel/effect FC on skin the same at 60 CYA/4-6 FC as it is with 80 CYA/6-8? I’d rather not have to lower my CYA since I just raised it.

 

[wireform]

I don't think you will notice any difference with those ratios but on either of those number sets the lower one is risky for aborting an algae breakout so stay in the mid to higher end of that range.

 

[rack04]

What is the sensitivity? Respiratory? If so, this is likely a product of chloramines (monochloramine, dichloramine, and trichloramine) and not chlorine. What is your combined chlorine test result? If combined chlorine is present you will likely need to "shock" to breakpoint chlorination to oxidize the chloramines.

 

[dereksanders]

Dry, itchy skin is the result. That’s after rinsing after she exits the pool and applies lotion. While sleeping she scratches herself to the point of having blood spots all over the sheets. We have a whole house filter that helps quite a bit.

Since I’ve slammed the pool in early June my highest CC reading has been .5. This morning’s tests after thunderstorms all night show:

FC - 5.5
CC - 0.0
TA - 70
PH - 7.4

 

[kul]

I’m so sorry to hear this! Was there a chlorine level that was working well for her? Maybe use that as your guide and adjust the CYA so that it’s in line with the FC that she is comfortable with?

 

[Newdude]

Can she shower ok ? Tap water with 0 CYA and 1 FC has a harsher HOCL content than slam FC does per your CYA. And tap water may have up to 4 FC.

I had 3 friends back in the day with skin issues that would only swim at my house, and I was running FC over target the whole time.

If tap water isn't a problem too, but the pool now is, then the CYA may be off from what you think it is. (Being subjective and all, it gets every one of us at times). Last year you weren't on TFP obviously so those issues don't count now if you're balanced to TFP specs. I'd suggest getting the CYA sample mix for comparison of your own. (At tftestkits.net) It's only a few bucks for the peace of mind that you're sure you're looking at the googley eye correctly.

Also Overnight Chlorine Loss Test to prove nothing else is going on as a smokescreen to blame the FC.

 

[Mdragger88]

Derek- all of the levels in each column on the chart are equivalent for the various cya levels in terms of “active” chlorine (layman’s terms)
ie; a cya of 60 & fc of 4 is no different than a cya of 80 & fc of 6

Chlorine/CYA Chart

EDIT: You will find a simplified and standardized version of this chart at Pool School, Chlorine / CYA Chart. Chlorine/CYA Chart by Chemgeek FC = Free Chlorine in parts-per-million (ppm) CYA = Cyanuric Acid in parts-per-million (ppm) CYA ........... Min FC3 ..... Target FC ...... Yel/Mstrd...

www.troublefreepool.com

Perhaps try as @Newdude suggests & really confirm your cya level.
Has this always been a problem with your pool or a recent thing? Maybe not pool related at all?
While there is no “perfect ph” (all 7’s are ok)
Some people can be more sensitive to low/high ph than others. So that’s a consideration.

 

[reggiehammond]

Does she wear the same sunscreen she uses in pool at times when not swimming?
What are you using to lower pH?

 

[dereksanders]

Thanks all. Yes, she has issues with tap water which is why we have a whole house filter in the last two houses.

I pretty much do an OCLT every night because I’m slightly anal and want to catch anything early. I didn’t last night because I ran SWCG last night in preparation for the storms. I pulled out quite a bit of debris this morning and getting ready to vacuum the rest of the smaller stuff out.

It’s overcast so I’m not going to do a CYA test today, but we will at the first opportunity.

No sunscreen for this little ol’ Italian lady. She not in the pool or sun for very long.

 

[dereksanders]

Only had to lower pH once and used Acid Magic 11 days ago. Dropped it from 8 to 7.6.

 

[dereksanders]

And last year was a Crud shoot. My guess is the FC was nowhere close to where it needed to be. We didn’t start using a good test kit until late in the season.

 

[Newdude]

Yeah. We can definitely dismiss the pre-TFP days.

Get the sample mix so you can rule that out. So many times the answer is more chlorine, not less. But this could certainly be the fluke of course.

 

[dereksanders]

Ordered the sampler mix and more reagent. Thanks.

 

[dereksanders]

OCLT showed no loss of chlorine overnight. The wife and I will both look at CYA today as it’s nice and sunny. I’ll recheck and verify once the sampler arrives.

 

[PoolStored]

I’ll recheck and verify once the sampler arrives.

For clarity with the standard sample. Use the standard sample as replacement for the pool water. Fill the mixing vial/bottle 1/2 way with the sample, fill with reagent. Mix. Pour to the 50 line in the view tube. Hold at your waist, outdoors, sun at your back, glance down. That is what the test should look like when done.

 

[dereksanders]

We both saw the dot disappear between 70-80, thereby making it 80. I’ll still verify our eyesight when the sampler arrives.