TF100 Stabilizer test

[Mike5150]

I'm sure you guys are sick and tired of questions on this test. It seems like it should be such a simple test, but I am doing something wrong because over the last week and a half since I got the TF100 test kit my stabilizer readings are 50 80 45 and 70, with several other tests that somehow didn't get recorded but were bouncing all over just like these. We often wind up testing chemicals at night, so I don't know if the lack of natural indirect light could cause such variations. I've seen mention of cheap natural light simulators, but the limited searching I did turned up a few contraptions that were on the pretty expensive side. Here is our procedure and hopefully someone can help me figure out what we are doing wrong.
1. Fill test bottle to the bottom of the label, and place in front of a space heater while we test the other chemicals (pool water is about 55 degrees right now)
2. Fill test bottle to the top of the label with R-0013.
3. Shake for about 30 seconds
4. Let sit for 2-3 minutes
5. Shake again for a few more seconds
6. Pour it in to the tube slowly with a white piece of paper under it, holding it at about waist high until black dot is completely gone.

When we do the test outside in indirect daylight we tend to get a lot of glare that makes it hard to tell if the dot is there. As I said earlier we have done the test inside and out, but I don't know if the lighting could cause such big deviations. It's possible that the numbers could coincide with inside tests and outside tests, but I can't remember. Hopefully it's something as simple as that!

Thanks!

 

[PaulR]

For outdoors, try someplace a little shadier to avoid the glare. I usually end up under the trees, otherwise I get too much sky reflection off the top of the sample in the tube. Or, I do it indoors near a well-lit window.

Brightness matters more than color. You shouldn't really need a sunlight-spectrum light, but you do need enough light to be somewhere in the outdoor-indirect ballpark.

If you weren't keeping track of which tests were indoors or out, it will be harder to figure out if the light level is a problem, yep.... and remember you can pour the sample back into the mixing bottle and do the black-dot part again, just to make sure each individual test is giving you a consistent result (even if tests on different days are not consistent).
--paulr

 

[JasonLion]

Taylor recommends standing outdoors in direct sunlight with your back to the sun so your body shades the view tube.

 

[Thinkly]

I also have a new TF100 kit and am having the same issues. My pool store says my CYA test is 50. My test kit gives me results that don't even hit the graduated areas, in other words they are over 100. It doesn't add up. Maybe the pool store is wrong but I have replaced a LOT of water in my 9000 gallon pool. (my sig needs updated) I drained below the returns last fall, then added water. Then added more at opening. Also had to drain about 2" off of it last week do to heavy rains. In addition I usually have to add an inch or so every few weeks due to evaporation.

 

[JohnT]

I also have a new TF100 kit and am having the same issues. My pool store says my CYA test is 50. My test kit gives me results that don't even hit the graduated areas, in other words they are over 100. It doesn't add up. Maybe the pool store is wrong but I have replaced a LOT of water in my 9000 gallon pool. (my sig needs updated) I drained below the returns last fall, then added water. Then added more at opening. Also had to drain about 2" off of it last week do to heavy rains. In addition I usually have to add an inch or so every few weeks due to evaporation.

Do your test, then pour all of the mixture into a larger container with an equal amount of distilled water. Pour the mixture back into the graduated cylinder as you do when normally doing the test. You should see half of your previous reading. If you really want to check, take a sample of equal parts pool water and distilled water and have the pool store test it. Don't tell them what you are doing. Their results should be half of their previous results.

 

[Thinkly]

Would tap water suffice? (save me a trip to the store or boiling)

 

[JohnT]

Would tap water suffice? (save me a trip to the store or boiling)

Yes, for CYA, but not for any of the other tests since the contents of the water is unknown.

 

[JohnT]

If you REALLY want to be sure, TFTestkits has a standard 50ppm CYA solution http://tftestkits.net/R-7065-CYA-Standa ... n-p34.html that you can use to calibrate your testing technique.

 

[mynewpool]

If you REALLY want to be sure, TFTestkits has a standard 50ppm CYA solution http://tftestkits.net/R-7065-CYA-Standa ... n-p34.html that you can use to calibrate your testing technique.

Never knew this existed, thanks.

 

[JasonLion]

You can do the CYA test over and over with the same sample, as long as you are within a couple of minutes of when you first did the test. This means you can get extra practice with a sample whose level won't change to see if you get the same reading each time and to experiment with what having the black dot completely disappear means.

 

[anonapersona]

I always keep adding drops until I cannot be sure if there is a circle or a square, or at least that is what I ask myself as I am testing.
It also helps to ask a second person to do it right after you do, to see if you are pretty close.

 

[Mike5150]

I don't have a problem telling if the dot is gone, my issue is that my test results are jumping all over the place, and from what I understand stabilizer should not really move at all unless you replace water or add cya. I will test it tomorrow outside in the sun with my back to the sun as someone has suggested. Then maybe I'll do the test over inside with the same sample to see if the lighting makes a big difference. Any other suggestions would be great! Thanks again everyone!!!!

 

[PhillipH]

I'm actually in the same boat. My first CYA result with my new TF-100 kit showed 40ppm CYA (4/23). I tested again on 4/25, and I got 55ppm. Tested again on 4/29 and got 55ppm. I figured I just messed up on my first test on 4/23. I added 2 lbs of CYA this past Saturday 5/1. I tested again tonight (5/5), and I got 40ppm! I know it can take up to a week to absorb/dissolve all CYA, but still, that's a strange result. Unlike my pH readings on that awful color scale, I actually feel pretty confident about my CYA readings. I feel like I know exactly when the dot disappears, and I feel like I'm testing very consistently.

In all cases, I tested multiple times with the same sample and got consistent results.

Water temp around 70 degrees or slightly above in all cases.

To add the 2 lbs CYA this past Saturday, I poured about 1/2-lb at a time into a bucket filled with water and let it dissolve. I would pour the dissolved portion from the top into the pool, then fill with water and dissolve what remained in the bottom. I kept doing this over and over until I got the full 2 lbs in the pool.

 

[Pisces]

If you REALLY want to be sure, TFTestkits has a standard 50ppm CYA solution http://tftestkits.net/R-7065-CYA-Standa ... n-p34.html that you can use to calibrate your testing technique.

Thanks JohnT!!! I didn't know about this either, and will order some to test my skills after a year of doing the dreaded CYA test. I have more of a feel for it now, but it'd be nice to see how accurate I am.