Extended Test Kit Directions

[UnderWaterVanya]

Is it possible to Accurately do the FAS-DPD test w/ 10ml samples? It seems like you could do this by using a level spoon of the DPD powder and cutting down the reagents and lose precision to perhaps 1ppm. This might be useful when shocking to save on the amount of reagent used.

I tested this tonight on a 12ppm sample and got the correct number using this method.

 

[jblizzle]

10ml sample is what gives you the 0.5ppm precision. You would have to go down to 5ml to reduce the precision to 1ppm ... And I can not say if that is a good idea or not.

Posted with Tapatalk ... sorry if I sound short ... hate typing on phone

 

[duraleigh]

A 10ml sample is what is suggested and normal in the TFTestkits TF-100.

A 5ml sample gets really borderline on any precision and the benefit of the FAS/DPD is precision.

 

[JasonLion]

UnderWaterVanya, the amount of powder required varies with the FC level. One level spoon will give invalid results when the FC level is higher than normal.

 

[UnderWaterVanya]

UnderWaterVanya, the amount of powder required varies with the FC level. One level spoon will give invalid results when the FC level is higher than normal.

I knew it did with the normal sample but thought that at 1/2 the size there would be enough. My one test was accurate (matched the 10ml test) but that does not mean it would always be so I guess. I realize that this drops precision but when shocking to 20ppm or so, I was hoping it was a way to get good ballpark numbers with less chemicals and less time.

I may invest time and chemicals in validating this approach. I would be happy to keep records and post results comparing my tests using both sample sizes. Or I can just keep this to myself.

 

[chem geek]

If you're just trying to get an approximate reading of a high FC level, then using a 5 ml sample isn't terrible for that. It roughly doubles the error from misreading the sample size. For high FC levels where this technique would be used, figure instead of a 10% error you might be off as much as 20%. If you're shocking and you are conservatively on the high side above recommended shock levels, then that may not be much of an issue.

 

[UN1017]

pH

Notes

• It is easiest to read the color chart when the sample is brightly illuminated. Holding the sample cell up to a sun lit white surface (sheet of paper, white wall, etc) usually gives the best results. When testing indoors, it helps greatly to have a light box that provides simulated sunlight
  ....[/*:m:1fj30m2j]
• The precision of the measurement varies with your skill at distinguishing colors. With practice it is possible to read the level to +-0.1 or better, though many people will get results that are +-0.2 or worse.[/*:m:1fj30m2j]

I find I get better results when I hold the test block at arms length, with a white background of some sort. Up close it often appears I have a perfect match, but at a distance, I can see a different shade.

Somewhere there's a noob who can use this tip.

It seems that most of the "advanced" tests are pretty straigtforward. Funny, pH seems to be the most questionable for me. I usually do my testing at the kitchen counter and record my results on a spreadsheet. (geeky...I know).

I had a :idea: moment tonight. I turned on my laptop, opened a blank document (i.e. Word, Notepad). Did my tests and held the block at arms length about two inches from the white screen. It back-lit perfectly even. No hot spots etc. Just be careful not to spill it on your keyboard.

Try it. Let me know what you think.

 

[linen]

Welcome to tfp, UN1017

That is a great idea! I will give it a try when I get a chance.

 

[bpw3000]

I received a TF-50 kit today, but my blue scooper for the DPD powder was not in the package. Is there any other way or measuring this stuff or do I need to try and get a scooper sent to me?

 

[Bama Rambler]

You can just use the tip of a popsicle stick. About 1/8" is plenty. Until you can get the scoop.

 

[crustfan]

In the DPD Chlorine Test notes:

The precision of the measurement varies depending on the level being read. At 0.5, or 1 the precision is around +-0.5. At 2 it is around +-1. At 3 or 5 it is around +-1.5. When used with dilution the precision numbers should be multiplied by 2 or 4 (the same number you multiply the result by).

As 4JawChuck pointed out in an earlier post, the multiplier for the 1.8ml sample is 5. The notes were changed in the first bullet but not the last one quoted above.

If doing the OTO chlorine test and the pH test at the same time, read the pH color first then chlorine.

Is this because yellow is an irritating color and should be viewed after looking at red?

Anyone notice that the led's of the Speedstir give off a pinkish color. I need to shut them off when doing my FAS/DPD tests.

 

[JasonLion]

crustfan, thanks for reminding me of that 4/5 issue. It is fixed now. Staring at the yellow OTO color can bias your visual system, causing the PH results to look different. Also, the TC color can take several seconds to settle down, and it is simplest to read after it has gotten to it's final value.

 

[Kermiter]

Greetings! When I perform the TF-100 Calcium Hardness (CH) test, instead of the water turning clear blue, the solutions seem to "clump" together into tiny blue particulates in the sample and floating on the surface. Is this a normal result, or should the water be coming out clear at the end of this test?

Attached are two photos, looking from the side, and top-down. The white thing on the bottom is the magnetic piece for the stirrer. It's completely white.

Does the test come out clear blue for anyone? If so, I'm wondering what it means to have it come out the way I'm seeing it...?

(I have recently converted to a salt water chlorine generator.)

Thank you!

[attachment=1:d6fz1a5o]IMG_2420.jpg[/attachment:d6fz1a5o]
[attachment=0:d6fz1a5o]IMG_2421.jpg[/attachment:d6fz1a5o]

 

[UnderWaterVanya]

I don't have the speedstir - and mine doesn't look like that at the end.

 

[UN1017]

Are the specks always blue or do they change to blue when the rest changes?

Take a look at the thread below.

taylor-calcium-hardness-test-wierdness-t19126.html

 

[Kermiter]

Thanks for pointing me to that link. I repeated my test using both additional steps: 5 drops of 0012 before adding 0010, and using 8 drops of 0011L instead of 5 drops. The sample was then clear blue (same CH result as my previous run) with just a little bit of the "globs" floating on top.

I also had Leslie's test my water. Their CH test didn't produce any globs, and their CH reading was 100 ppm less than what I got with the Taylor test. I could see their test was the same as mine, but I don't know if they were using the Taylor kit or something else. The kid behind the counter didn't know, either. I will stop in again sometime and ask the owner. FWIW, Leslie's has never found metals in my water, so I doubt that's what is causing the globs.

 

[duraleigh]

Kermiter,

I post this daily and there may be a few exceptions out there but I don't think there's ever been a report of pool store testing being better than your own. Time and time again, pool stores fail to test water correctly but people new to the forum tend to trust pool store tests because they do not have confidence in their own testing.

Your own testing will probably be correct 95% of the time at least. It is a mistake to go into a pool store to compare your test results as it only leads to doubt and confusion.

Of course, I have a bit of an agenda in that I sell the TF-100 but I want to assure you that the two kits this forum likes, the TF-100 and the K-2006 are the most reliable kits on the market and superior to virtually ANY pool store results.

TRUST YOUR OWN TESTING!

 

[UnderWaterVanya]

When dealing with high CYA (> 100) can you take the solution you made with 100% pool water and dilute it after already making it? Can you salvage the reagent you used and dilute to 50/50 or 33/66 in order to get a better estimate? Or do you have to start with a tap water diluted sample from the begining?

 

[chem geek]

Yes, you can dilute it after you've already mixed it with CYA reagent. Basically, the CYA reagent has an excess of melamine so the amount of turbidity is a function of how much CYA is in the water. If you dilute 50/50, you cut down the amount of CYA in half. Whether you do this before you've added CYA reagent or after doesn't matter. If you do it before, then you cut down CYA in half before it binds to melamine. If you do it after, then you cut down the already bound melamine cyanurate in half. Either way, the end result will be the same.

 

[UnderWaterVanya]

Yes, you can dilute it after you've already mixed it with CYA reagent. Basically, the CYA reagent has an excess of melamine so the amount of turbidity is a function of how much CYA is in the water. If you dilute 50/50, you cut down the amount of CYA in half. Whether you do this before you've added CYA reagent or after doesn't matter. If you do it before, then you cut down CYA in half before it binds to melamine. If you do it after, then you cut down the already bound melamine cyanurate in half. Either way, the end result will be the same.

This seems like important info particularly for those using Taylor kits with limited CYA tests.


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