I dont use hanna checkers. They are inaccurate. And they are expensive. Do 2 tests in a row. Guarantee they will be different numbers. Mine always where!
I get zero readings for nitrates and 0.03-0.06 with RedSea test kits. And I know my nitrates are not zero! No way! And I know my phsophates are not 0.03 becasue I had quit a bit of algae growing. The algae will mask the test results. Looks low because the algae is consuming it.
I have no experience with Zeovit colors. Too pastel for me. I like deep rich metallic colors. I feel they look way more natural. But everyone has their opinion.
In all fairness to Hanna, maybe I had bad batches of test reagents. Not sure, but I used them for a while and then just ditched them. Too much erratic results....