Red Sea test kit - question for those who use it.


Reefing newb
When you use the titration kits for Ca, and Mg, do you record the readings as soon as the color changes?
Or do you wait a few seconds to see if that color holds?

This is what I have been experiencing lately with my test kit.
For example, the Ca test:
1.When I start adding the titrant, the color changes from pink to blue at a certain point (for example, 400ppm equivalent).
2. I put the kit down to record my readings and when I look at the vial for the Ca test a few seconds later, the water is pink again. I add one or two drops of the titrant again and this time when it turns blue, it stays blue that for a few minutes.

So I want to check, which reading is the correct reading? The moment that the test sample initially changes color (despite reverting colors a few seconds later)? or when it gets to a point where it stays blue?

Sometimes it takes up to 4 additional drops after the initial test to change the color to blue and get it to stay that way, which is a significant value swing compared to the initial readings.

I have not observed this on the Alk test, and just to a minor degree for the Mg test.
Yeah I think ones you see it change and it changes back really quick then maybe another drop or 2 should be it, Well that how I do mine.

I was having issues with the MG test in my kit reading way high compared to my Salifert kit.

Salifert kit was reading about 1400 ish and red sea was reading 1600

I called Red Sea and they shipped me out a new MG Kit quick ones I tested again I got the same results of 1600 I was like WTF.

So then I used the 2ml syringe from the salifert test kit and I got the 1400 reading on the red sea kit. it seems like ither the Salifert Syringe is slightly lower in the actual water volume when compared to the Red Sea syringe. So im not sure with one to trust...

If this would be the case do that would mean when using the RED SEA syringe for the other 2 test it should actually be a little lower on my reading also. So im like WTF lol. its a pain in the ass.
The 1st stage of the Mg test is the tricky part.
You have to stick to the "shake for 15 seconds per drop" of the first reagent.

I have tried taking shortcuts in the past and the results were off by about 100-200 ppm.
So I took some reading today of my Tank and the freshly mad water change water and here what I got.

Fresh water was at

Ca. 500
KH 11
Mg. 1530

My tank is at

Ca. 380
KH. 7.1
MG. 1480

Im hoping to get the KH and Ca. up a bit so im using kalkwiser for a bit to bring that stuff up. im not sure why my ca. reads so low I use to test with elios test and that one alwys read 430 to 450.