New Pool Owner - Different Chlorine Tests, Different Results

440dodge440 · May 8, 2015

Hi,
I got the pool looking pretty good (a little dirt left to vacuum, but very clear water). I'm using a few different tests to try to make sure I'm not doing one wrong and relying on those results. So here's what I have:

Taylor Basic from TF-100: Tests TC. At first registers 0.5-1. After several minutes, the color darkens to 3-6. There are no timeline instructions.

DPD/FAS Test from TF-100: I find it important to let the powder stir for a few minutes to prevent adding the liquid reagent too soon. When I do this, I get a fairly consistent 4 FC and .5-1 CC

Poolmaster 5 way Test Kit (came with the house- was outside all winter)- Instructions say 'within 2-3 seconds, compare color- this is FC. Wait 1-2 minutes and compare color- this is CC'. The pool tests at 1 FC/3 CC

HTH 5 Way Test Strips (came with the house- was outside all winter)- No reading on the FC square, but if I dip it in bleach it doesn't read either- Defective, or does it not read chlorine in bleach somehow?

None of these seem to correlate to one another. As I said, the water is quite clear (see picture). Any thoughts?

woodyp · May 8, 2015

Trust the TF-100 results.......and you will even more with more testing experience. No need to "wait a few minutes"----just swirl and add your drops. Stips are worthless even without being outside all winter. Pitch the poolmaster as well if it's been outside.

duraleigh · May 9, 2015

+1 what woody said.

Use the Taylor K-1000 (it's the blue box in the TF-100) as a test for the presence of chlorine but not for accuracy. When you need accuracy, use the FAS/DPD chlorine test (with the powder).

Toss the others.......they will only confuse you.

440dodge440 · May 9, 2015

Thanks...That makes me feel better. How often do you test using the FAS/DPD method? Is it daily, or weekly as stated in the instructions? Also, how often do you add stabilizer?

tim5055 · May 9, 2015

440dodge440 said:
Thanks...That makes me feel better. How often do you test using the FAS/DPD method? Is it daily, or weekly as stated in the instructions? Also, how often do you add stabilizer?

it all depends on what your "normal" FC should be based on your CYA level. Why my CYA was 200+ and I had to keep the FC around 20 the K1000 didn't get a lot of use because I needed the FAS/DPD to tell,me I was,in the correct neighborhood. Now that my CYA is down and my FC range is 4-6 I used the K1000 daily to doublecheck the color is bright yellow (5ish) and weekly I use the FAS/DPD to verify things.

Generally the only way for,stabilizer to go down is to pump out water, so I only check It a couple of times a season. If you are in a rainy climate and pump,water out of the pool regularly you may need to add CYA every once in a while, but it's not common.

440dodge440 · May 9, 2015

tim5055 said:
it all depends on what your "normal" FC should be based on your CYA level. Why my CYA was 200+ and I had to keep the FC around 20 the K1000 didn't get a lot of use because I needed the FAS/DPD to tell,me I was,in the correct neighborhood. Now that my CYA is down and my FC range is 4-6 I used the K1000 daily to doublecheck the color is bright yellow (5ish) and weekly I use the FAS/DPD to verify things.

Generally the only way for,stabilizer to go down is to pump out water, so I only check It a couple of times a season. If you are in a rainy climate and pump,water out of the pool regularly you may need to add CYA every once in a while, but it's not common.

Thanks...My CYA is in the 40 range, so I need the 4-6 FC. Do you also find you need to wait a few minutes for the K1000 to turn bright yellow or does it do it immediately?

tim5055 · May 9, 2015

440dodge440 said:
Thanks...My CYA is in the 40 range, so I need the 4-6 FC. Do you also find you need to wait a few minutes for the K1000 to turn bright yellow or does it do it immediately?

put the drops in, a little shake and its immediate.

Casey · May 9, 2015

As you start testing your water, you will start to understand your pools satiable diet for chlorine. As bather load goes up, your chlorine should too. For example... My husband and I are the primary users of our pool. I keep the pool at 5FC with a CYA of 40ppm. For the last 2 days, I've actually bumped my FC up to 8ppm because I've had an 8 yr old, a 15 yr old, a boxer and a Rottweiler in the pool. Heavy bather loads just require more FC.