# Thread: Not sure if testing right

1. ## Not sure if testing right

Had to SLAM pool this week bad algae problem. Anyway Last night i do a test before I go to bed to do the overnight test and I get a FC=32.5. Being the clean freak my wife is she accidentally throws the paper out with my reading on it. Instead of going through the trash I figure I will just do a new test. So my next reading is FC=34. Then my curiosity gets the best of me because I wasn't sure the two numbers were the same and I get the paper out of the trash. So now with two different numbers I said what the heck and did another test. Well this one comes in at FC=35. So here is the real question is there a margin of error in these test or am I doing something wrong ( followed directions exactly ).

2. ## Re: Not sure if testing right

Are you adding drops until the last drop makes no change?
The numbers you got are close enough to be considered the same.

3. ## Re: Not sure if testing right

I want to do the OCLT so what number should I use so I can test in the morning.

4. ## Re: Not sure if testing right

How long did you let the water mix before taking the readings?

5. ## Re: Not sure if testing right

If your asking how long I mixed the water and the powder before I added the drops I would say about 2-3 minutes.

6. ## Re: Not sure if testing right

Sorry, should have been more specific. How long did you let the pool water mix after your last chlorine addition before taking the test?

7. ## Re: Not sure if testing right

Here are the Extended Test Kit Directions that go into a bit more detail on the testing procedures.

8. ## Re: Not sure if testing right

Every test has a margin of error. The FAS-DPD test with Taylor reagents (K-2006 and TF-100 both use Taylor reagents) can be off by up to 10%, so like Bama Rambler said, those values are all within the accuracy of the test. They are the same.

If you have clear water and CC at 0.5 or less and are within 1ppm of the lowest resulting FC value (32.5) in the morning, try letting your FC fall below 15, and then repeat the OCLT just to confirm.

9. ## Re: Not sure if testing right

My pump has been running 24/7 and my last dose of chlorine was at around 4 pm and did test around 8-830 pm. Will do test again when it drops to 15. Tested it tonight ( 8:30) and got a reading of TC=29 without adding any chlorine today. Going to do OCLT test tomorrow morning anyway figure it won't hurt anything. BTW CC is below .5 and pool is CRYSTAL clear (looks the best it has ever). Thanks for all the input.

10. ## Re: Not sure if testing right

I meant FC=29

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