Alk:
•Hanna: great, but reagent can get pricy.
•Red Sea: quality varies as it’s hard to read the color change sometimes, but I use this as a redundant test.
Calc:
•Red Sea; Color change is very consistent and easy to determine.
Mag:
•Red Sea; Color change is also easy to read, but testing has many steps.
Amm, Nitrite:
•API; it’s cheap and good enough to determine readings of 0.
Nitrate:
•Red Sea; easy to read only after practice. Very precise measurements that go down to 0.25ppm
Phos:
•Hanna Phos ULR: Very precise measurements