Salifert test kits: Speed of adding Reagent question

[snapcrackler]

Regarding the Salifert Marine Alk and Ca tests (which I really like), I have a question about adding the reagent (the last step in the process)

The instructions indicate to add 1 drop of reagent, then shake the test solution a little, then 1 more drop, then shake a little, and so on.

To save time, i.e. if you know approximately how much reagent you'll need to get you close to the point where you're adding those "last drops" with a shake inbetween to achieve the final color change, my question is this:

Does it skew the test results at all to shoot those first 20-30 drops in without shaking between each one?

Or, is the test user instructed to do this simply so as to not "go past" the point of color change, (overshooting)

I was going to sit down and do about 5-10 controlled tests right after the other from one tank, just to see if I got different results with shaking or not shaking with the first 50-70% of added reagent. However I wanted to check with y'all first.

TIA!

Erik

 

[cj10488]

I have not had any issues going about the method you are descibing.. I usually start with the normal 1ml and bring it down to about .1 above where I believe my levels should be.. Shake it real good and continue drop by drop until it changes color... Always comes up with the same results.. Habib over at Salifert also states this method shouldnt cause any issues at all.. I think that most that of us that use salifert at some time did this metod with any issues..

HTH<
James

 

[snapcrackler]

Excellent! That will save a lot of time each time I test. I thank you all for doing this research (that saved me some time too!)

Erik

 

[Brad]

titration reaction

This is a standard titration..the color change is caused by the total amount of the added chemical depleting another chemical in the test volume..in the presence of an indicator. The total amount added is the only factor..not the speed at which it is added.

The only risk is that, in your haste, you overshoot the end point. If you do this you have no result.