Impossibly High Fc Reading With K-2006 Kit?

[Flowbee]

Hi all - I've recently become the owner of a 20,000 gallon gunnite pool (my first pool). Just received my K-2006 test kit today. My FC tests are off the charts; in fact, I can't get the test water to clear from pink, even after adding more than 40 drops of R-0871 (using the .5 per drop basis). My CYA is 100, but the pool is quite cloudy and I haven't added any chlorine for several days (I was waiting for my test kit before I started shocking). It's hard to believe my FC is over 20, so I'm wondering why I might be getting this result from the test.

Any clues?

[2n3055]

Are you adding the right reagent, R-0871?

[waterbear]

There is a good possibility that your CYA is much higher than the 100 ppm that is the upper limit for this test, expecially if the pool has been chlorinated with either trichlor or dichlor for any length of time and even more so if you have a cartridge filter or a bump type DE filter. Thie high CYA would explain the very high FC levels AND the clooudy water.

I would take a sample of water and dilute it with an equal part of DISTILLED water and then retest the CYA and chlorine.

Multiply the CYA test by 2 to get the approximate reading. If you are still at or over 100 ppm (and there is a good possibility you are) you will need to do a partial drain and refill to get the CYA down to a manageable level.

When you do the Chlorine test each drop will now equal 1 ppm.

realize that by diluting your sample you are decreasing the precision of the test so this is not a procedure to do on a regular basis but only under special conditions such as you are currently experiencing.

IF you have an OTO chlorine test (comparator is shades of yellow and is usually found in inexpensive 2 way testers) test the water with that. If your chlorine levels are as high as the FAS-DPD test indicates the OTO test will turn dark yellow to orange/brown in color. OTO only tests for TC, so the info it gives us is not that useful, but is a bulletproof test that does not suffer from bleachout or other interference, even at extremely high chlorine levels. This makes it an excellent test for either:

1) a quick daily check to make sure the chlorine in the pool is about where it should be ( as long as you are breaking out the big kit weekly or whenever there is a problem ,whichever comes first).

2) to verify that there is a LOT of chlorine in the pool (the OTO color will go from dark yellow to orange to brown as chlorine levels go up and up and up. At normal shock levels the color of OTO ranges from dark yellow to orange. Brown indicates extremely high chlorine levels!

Hope this helps.

[Flowbee]

Yes, I've double- and triple-checked that I was using the right reagent.

I also did do the 50% dilution test on the CYA (per advice in these forums) and came up with a reading of 50. So I think I'm right around the 100 range for CYA.

I'll pick up an OTO test today and see what color I get.

Thanks for your help.

[Flowbee]

Well... I guess I have fantastically high chlorine levels. The OTO test turned the water dark orange. Crazy. The last time I added any chlorine was last week... on the advice of the pool store after they tested the water. When the water didn't clear up, I was sure I'd have zero FC, like the majority of "cloudy pool" posters. Huh.

So now I guess I drain 1/3 of the pool water and replace it, maybe a couple of times, to try and bring the CYA to 50 or so.

Any other advice?

Thanks.

[waterbear]

So now I guess I drain 1/3 of the pool water and replace it, maybe a couple of times, to try and bring the CYA to 50 or so.

Any other advice?

Thanks.

Once you get the CYA down to between 30-50 ppm post a full set of test results and we can see what is needed next.

[Flowbee]

So here's the follow up...

I drained about 1/3 of the pool and re-filled it, which brought my CYA down to around 60. Then I did another chlorine test, this time diluting the pool water with 3 parts distilled water and got a FC reading of 48 (!!) and a CC of 0, so I guess I had sufficiently chlorinated the water prior to the refill (and then some). I've spent the past week vacuuming, brushing, skimming, and filtering the pool and I'm happy to report that the water is now crystal clear. My current test readings are:

FC = 14

CC = 0

TC = 14

pH = 7.6

TA = 90

CH = 300

CYA = 60

I haven't added any chorine since the refill, and it's dropping about 6 ppm per day (with the help of some afternoon rain showers).

My original concern was that the water was still cloudy even after I was pretty sure I had shocked the pool properly. Looks like I just needed to brush and filter for about a week to clear all the dead algae that was clouding the water.

Thanks for the help.