FC higher than 10ppm?

[waterflea]

I am a new pool owner (never had a pool before). I had a pool company doing the cleaning services until last week when somewhat had a feeling that they were not doing things right and fired them. Today I received the K-2006 test kit and did my first testing.

I followed the FC steps and did the test 3 times. The water does not become colorless even after 20 drops on the 10ml sample which means I am already at 10ppm FC.
I also tested CYA and the reading is 80ppm.

More context...
I saw the company using liquid chlorine but when I opened the chlorine feeder I noticed 2 tablets.

Is this possible over 10ppm FC? How can I lower the FC?

 

[Texas Splash]

Welcome to TFP! If you are using the 10 ml water sample and dividing the results by 2 (0.5), then yes, an example would be something like 40 drops = an FC of 20. But don't stop, keep going until it turns clear to find your true FC. As for "if" it's too high, simply look at the TFP [FC/CYA][/FC/CYA]. You can see that for a pool with a CYA of 80, you have quite a bit for room to go high. Don't worry, as long as you are not feeding the pool chlorine, the FC will drop. Definitely remove those tabs though. They add CYA and you don't need anymore.
ABCs of Pool Water Chemistry

Oh, and please update your signature with all of your pool and equipment details.

 

[waterflea]

Thanks. I just did another test of FC. 38 drops X 0.5ppm = 19ppm FC. Seems to me very high...I don't think I need this concentration.

 

[Texas Splash]

19ppm FC. Seems to me very high...I don't think I need this concentration.

19 may seem high, especially if you mention it in a pool store, but once you see the FC/CYA correlation on the [FC/CYA][/FC/CYA] you know it's still okay. It should fall in a matter of a day or two with good FL sunshine and no additional chlorine added. Once it falls down to the recommended FC range you see on the [FC/CYA][/FC/CYA], simply try to keep it balanced in that range with some regular bleach or liquid pool chlorine. If you use bleach, make sure it's NOT splashless and contains no scents or fabric polymer products. Just the plain stuff.

 

[Donldson]

If your CYA is 80 then your 19 FC is quite safe. Anything below "Shock FC" according to the [FC/CYA][/FC/CYA] is safe to swim in. Yes, that means you can swim up to 31 FC, the CYA buffers it so much that it will feel and act less harshly as most indoor public pools (which typically are required to use zero CYA).

It usually is quite a shock (um, no pun intended) when you first hear those kinds of numbers are safe, but one of the cores of TFP is understanding what CYA does in regards to buffering chlorine. Not recognizing this is one reason traditional pool care often fails and includes a lot of extras to keep algae at bay.

And let me throw in my Welcome to TFP! Glad to have you here.

 

[waterflea]

Thank you! Is there anyway I can lower the CYA over time without changing the water?

 

[aussieta]

80 cya is not a huge problem
cya does breakdown slowly
and gets diluted with splashout and backwashing if sand filter
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[ajw22]

Thank you! Is there anyway I can lower the CYA over time without changing the water?

No, you lower CYA by draining some water out of the pool or doing a water exchange. You will naturally lose some CYA during backwashing and splashout. But CYA does not evaporate when water evaporates from your pool.

 

[YippeeSkippy]

Being that you're in FL, with frequent rains, you could always drop an inch or three of water and let the rain refill that pool. This over time will go far in lowering your CYA via dilution.

Maddie

 

[waterflea]

Thank you all for the advice. So sounds like I can't use any tablets for a while. Only liquid chlorine. Correct?

 

[Texas Splash]

Thank you all for the advice. So sounds like I can't use any tablets for a while. Only liquid chlorine. Correct?

That would be best. No side effects as long as it's plain/regular chlorine without any additives. Shop around in your area for the best deals and always use the PoolMath tool to figure out your dosages. Make sure to update the "Weight" field with the correct bleach/chlorine percentage.

 

[ajw22]

So sounds like I can't use any tablets for a while.

A while being close to forever. You can't rely on tablets as your main chlorine source,

Only liquid chlorine. Correct?

Or install a SWG. With a SWG you are buying a few years of CL at one time. See Pool School - Salt Water Chlorine Generators