Low CYA, but high FC

[KathyCox1228]

When I test my water, the Ph is perfect. Alkalinity is great. CYA is low - 40-50, but FC is high. Kids are complaining their eyes are burning, so I'm thinking I need to decrease chlorine. But if my CYA is low, why am I maintaining high cholorine? The water feels great, is crystal clear and has a faint smell of chlorine, but not at all like a non-SWG pool. Water is mildly salty, not much. From where I sit, I feel like things are great even if the chlorine is high, but after a couple of days of complaints about eyes, I wanted to try to troubleshoot.

The pool is in direct sun. No shade at all, so I was expecting low CYA to be lowering FC.

Thanks for your helpful comments, as always!

 

[Donldson]

What is your actual FC? And how are you chlorinating?

Typically eye irritation is a CC issue, are you registering any?

 

[KathyCox1228]

Chlorinating with SWG. FC was just 5.0 and TC was 5.0, so CC is 0 using FC-TC = CC per the K-1004 test kit. I follow the directions on the test kit. I have had these numbers for at least 10 days in a row. I'm testing often so I can get a feel of this new pool. Just a few minutes ago: FC 5, TC 5, CC 0, Salt 3200, CYA 30-40. Although, I am about to do some research on the CYA test to make sure I am judging the results correctly. I suddenly thought maybe it's "administrator error" on the CYA. PH was 7.5. Again, these results for many, many days. We do have a pool heater and the water hovers around 85 degrees. It's awesome.

 

[IceShadow]

FC of 5.0 isn't very high for a CYA of 30-40.

FC/CYA Levels

 

[Donldson]

5 ppm FC is not in the least bit "high" for a CYA of 30 or 40. Of course, that test can only measure to 5 ppm, so there's no way of knowing how high your FC actually is...

I thought you said back in March you were getting one of the recommended test kits. Specifically, "Will definitely order the kits you recommend ". Why are you still using the k-1004?

 

[KathyCox1228]

The K-1004 is what I thought someone told me on this site to buy. Will review my posts/responses.

 

[IceShadow]

You want to get an FAS-DPD test kit - like a TFT-100 or a Taylor K-2006C. (The C is important because otherwise you don't get enough reagent to do more than a few tests.) See:

Swimming Pool Test Kits Compared

What pool test kit should I buy? Why not use test strips? Our recommended test kits will pay for themselves in no time!

www.troublefreepool.com

These will give you an exact measurement on your FC to the nearest 0.5ppm or so. Perhaps your FC is much higher than 5.0...?

 

[KathyCox1228]

Just went through my posts and I remember now, I went to order the new one and got the Salt kit and forgot to get the TFT-100. Just ordered it and will start again with a better kit. Thanks for reminding me that what I had wasn't optimal. I also just watched some videos on the CYA kit (Pentair Rainbow) and I'm testing it correctly from what I viewed. Thanks again for the help!

 

[IceShadow]

Let us know the test results when you get the new kit in. It could be high FC, but usually the culprit in situations like this is sunscreen in the eyes.

 

[KathyCox1228]

Let us know the test results when you get the new kit in. It could be high FC, but usually the culprit in situations like this is sunscreen in the eyes.

Will do! I would suspect sunscreen except I'm not sure my sons are putting it on regularly. Grrrr. I am enjoying learning all this chemistry. My boss is a chemist so I can impress him with my lingo.

 

[IceShadow]

For the record - it's safe to swim in water that's up to 12ppm of FC if the CYA is 30, or 16 if the CYA is 40. So it would have to be REALLY high for it to be an issue.

You'll probably want to bump up your CYA to 70 or so with the SWG, but don't do that until the new kit comes in and we get all the test results, just in case there's something off we want to address.