TF-100 test kit question....FAS/DPD test

[kris77]

Is it possible for the drops to be bigger than they are supposed to be coming out of the 0871 bottle?

Seems like my drops are very big and i'm getting low FC readings.

I cleaned the tip of the bottle and blew off the tip and they seemed to get smaller and now i'm getting FC levels that I expect to have.

I got a FC reading of 5.5 before I cleaned, and 9.5 after i cleaned it.

Does this sound normal or even possible?

 

[JasonLion]

That is possible, though quite rare. Almost always if there is a problem it is the other way around, smaller than normal drops.

Cleaning the dropper tip with a damp cloth or tissue is always a good idea.

 

[Vyrolan]

On the topic of drop size, one thing I rarely see mentioned here is the advice to hold the droppers vertically and be consistent with your technique. Some people will hold the droppers at an almost-horizontal angle and a much larger drop forms against the top via cohesion....then later when the bottle is less full they go vertical and get smaller drops. Maybe it's not enough of a difference to impact anything, but it's something I always think about when testing.

 

[JasonLion]

Vertical is indeed important. Most people get that right without being told, but it is worth mentioning none the less.

 

[timerguy]

I've seen where it's important to wipe the tip of a new TA reagent bottle, but don't think I've ever seen that talked about for the r-0871.

 

[JasonLion]

It solves a common problem with the TA test, while it is quite rare that you need to wipe the tip for any of the other tests.

 

[kris77]

I just kept getting low FC readings and was wondering why. Then I started paying attention to the drops and they just looked bigger than they used to. So I was getting about 1 1/2 drops to every drop. Once I cleaned the tip, everything worked out like I expected. And I had a SUPER high FC reading because I kept adding bleach thinking I was low.