N03 - Red Sea ( this kit has two methods, low range and high range which is awesome. If N03 0-4 use low range, if 4+ use high range method)
P04 - Hanna
KH - Hanna (this one is a must have imo)
Mag - Salifert
CA - API
I just got a Hanna for DKH as a lot of the titration tests I cannot tell the alk endpoint.
I use a salifert for nitrate as it has a reasonable color change
red sea for cal and mag
Hanna for Po4. however mine is not the ULR model. just phosphate so its rare it ever measures anything at all.
Thanks everyone. It seems pretty unanimous on Hanna for PO4 and Alk.
I'll do some digging on any sales on Red Sea or Salifert. That will likely make my decision for the remaining kits.