TFT testkit TF-100 question

[PearlandPool]

A couple of questions on this testkit. I noticed the description of the Combined Chloramines test says it can measure CC's down to 0.2 ppm. I was wondering how to achieve this measurement? The instructions say to add 5 drops of R-0003 after the FC test. If it remains clear there are no CC's (0 ppm) but if it turns pink to add a drop of R-0871 and when it turns clear to multiply by .5. So a minimum of one drop would be 0.5 ppm. Am I missing something?

Also, how reliable is the CYA turbididty test. I can never get that black dot close to disappearing, but when I take it to the pool store they tell me my CYA is 80. Is it possible to have a bad reagent?

Thanks in advance.

 

[JohnT]

Welcome to TFP.

The 0.2ppm accuracy is when you are using the larger sample size, which I think is 25ml. When doing the test that way, each drop is 0.2ppm. I can't see much reason to do it that way though.

 

[frustratedpoolmom]

Also, how reliable is the CYA turbididty test. I can never get that black dot close to disappearing, but when I take it to the pool store they tell me my CYA is 80. Is it possible to have a bad reagent?

The reagents are fresh, assuming this is a new kit?

Lets review your testing method. You add the pool water to the mixing bottle, and allow it to come to room temp (because cold water affects the results). You add the CYA test solution to the appropriate level. You shake it to mix. You let it sit for a minute or so, and then you shake it for 30 seconds.

Standing outdoors, with your back to the sun, so your body shades the view tube, hold the view tube waist high. Then you slowly pour the solution into the view tube, stopping when the dot disappears, and that's your level.

See this link for pics:
http://www.taylortechnologies.com/ChemistryTopicsCM.ASP?ContentID=44

So it could be you have no CYA and the Pool Store is wrong, or it's testing error on your end or the pool store. (wouldn't be the first time a pool store gave the wrong results.)

 

[PearlandPool]

Thanks for the quick replies. I'm impressed .

Definitely helps clear up some things. I got the test kit last year and followed the instructions provided with no success then either. I keep my reagents in a cool dark place, so i feel like they are still fresh. However, I'll try your instructions Frustratedpoolmom. They are a bit more detailed and slightly modified than the instructions given with the test kit. Maybe i wasn't letting it sit long enough or shaking it long enough the second time. I'll give it another try.
Wish me luck .

 

[frustratedpoolmom]

Good luck... the reagents from last year should be fine too.