Test Kit Reagents; when exactly are results viable?

[ReefRy]

Hello all. Ive been testing alkalinity, calcium and magnesium regularly with Red Sea and Salifert, but I assume the question I have applies to most kits:
At what point do I stop adding reagent?
1. As soon as a change in color takes place, no matter how minute?
2. Once the transformation (from pink to blue) is complete?

 

[Billldg]

I keep adding until I start to see a change from pink to almost blue, then I add a drop at a time until fully blue, then i add 1 more drop. After doing it a few times you start to see the transition more clearly.

 

[ReefRy]

That's exactly the way I've been doing it as well. Thanks, just wanted to make sure.

 

[Billldg]

The first couple dozen times I was so paranoid, but after a while you just start to see it more clearly, I guess as you get more comfortable with it.

 

[ReefRy]

I was comfortable (I thought), but then I started getting pretty decent variances in the results. I attribute that to my tank only being up since Sept 10th, but yeah, I also worried it was user error. Was I being consistent week in and week out, same time of day, same lighting, etc. I'm trying to eliminate as many variables as possible.

 

[primoleo]

Depends on the test. The calcium test says it has to turn to a clear blue color. The magnesium says gray or blue whichever observed first. Just read the instructions

 

[JimWelsh]

It very much depends upon the test. Like @primoleo said, read the instructions.