Red sea test kits colour change readings, which?

[atoll]

Bit of advice guys from those whonise thecredcsea calc and mag test kits. I have a Red Sea multi test set Calc Mag Alk.
When perfuming the mag and calc tests I have noticed a minute or so after the colour change to blue takes place the colour reverts back to purple. A drop or 2 more from the syringe turns it back to blue.
Right the question is which reading do I take as the most accurate, when they first turn blue or when I add another drop or 2?
Cheers.

 

[gbroadbridge]

A few years ago, Kev from Red Sea told me in an email that the correct reading is when the color stays stable for 30 secs, so effectively another drop or two nails it.

Can't find the email anymore, but thats how I read it and it matches Triton ICP pretty closely.

 

[atoll]

A few years ago, Kev from Red Sea told me in an email that the correct reading is when the color stays stable for 30 secs, so effectively another drop or two nails it.

Can't find the email anymore, but thats how I read it.

Cheers, I was leaning towards that and in fact makes my reading better than before I add the extra drop or 2.