Saifert for all except PO4 Hanna for that.

I have Elos for CA i have hard time to use it and i lost the spoon for the part B
and API for the rest of the things

Phosphate - Hanna
Calcium - Elos
Alk and Mg - Salifert

Those are the only things I check with any decent regularity.
I found the Salifert Ca test hard to read. I found the Elos Mg test tedious.

I voted salifert because I use that for Ca and Mg. Elos for Alk
Have not used my hanna for PO4 yet.

Thinkin' the Elos sales team needs to look at this poll :)

You missed the most popular test kit ever.... 'LFS' :mrgreen:

Seriously, Salifert and Hanna are my fav.

Elos here but last time I tried to get new ones I was told there is no NA dealer anymore. I still need kits!

You missed Hanna on the poll. I know it's covered under "Other", but it's a forerunner too.

Me too. I also use Hanna for phosphorus and alkalinity. I prefer elos over Salifert, but Salifert is more available, so I'm forced into Salifert often.

I left Hanna off on purpose, I considered it a meter rather than a brand of test kit. The poll asks for most popular (of your individual collection) of kit. I doubt more than one or two people have a full compliment of Hanna meters.

For me, I have mostly Elos, maybe a Salifert, so I picked Elos at the major brand in my setup

I also have an API for NH3, I find it quick and easy, and only need a yes/no value from it.