can the red sea kits be used for testing. my lfs uses red sea kits cause the seachem kits were bad, they say use the red sea between .2-.25 the test kit onle goes to .4 and cupermine says .5 for end result
Generally in test kits, you get what you pay for. LaMotte is much better than any of those kits, but I can't afford $70+ a kit.
If you go to the manufacturer's website, you should be able to get ranges and precisions for each of the test kits. The kit you use will depend on your purpose. If you want to bring Nitrates to 0, then you'd want to get a low/narrow range, high precision kit. If you want to get ballpark figures of your tank, then a wide range, low precision kit might be better for you.