I've only used one - API (liquid). I have heard that liquid tests are more accurate from a number of sources. Some of the colors are a little off or hard to read, but you do what you can.
MY TANK: Planted 10g; 2 x 10W CFL; Fluval U2 internal filter; MGOCPM/black sand cap
A Silent Cycled Tank
started April 18, 2012