I use the API SW master kit, and the API reef kit. They work well the only down side is the don't come with tests for Magnesium or Copper, and for what I can find API does not even make a Magnesium test kit.
I use the three that Carmie mentioned. They are as reliable as the operator. In other words if it says add 3 drops, don't add 2 or 4. That skews the results.
Dick
__________________ Amphibious
Reaching my 70th BD, I realize that I cannot help but grow old. However, I refuse to grow up!!! My wife would tell you, "He may be 70 but, He's going on 17". Life is wonderful with a woman like that.
I am using the TetraTest Kits since they were a gift for Christmas. I was looking to move to the API since they are affordable and have a good reputation.
I use Salifert (NO3, Alk, Ca, Mg, PO4) and Elos (Alk, Ca). I like Salifert for resolution and Elos for NIST standard compliance. You may want to check out this link for Salifert price comparisons.
I think any of the available digital test kits are reliable by their very nature. I haven't heard anything negative about them. I'm using an old (15 yrs) American Marine, Inc. Pinpoint pH meter and it works great. It's been in continuous use and I check calibration now and then just to be sure. I usually make a very small adjustment to "zero" it in.
Dick
__________________ Amphibious
Reaching my 70th BD, I realize that I cannot help but grow old. However, I refuse to grow up!!! My wife would tell you, "He may be 70 but, He's going on 17". Life is wonderful with a woman like that.
icon under their name to add to their reputation. 
Digital Test Kits ? 
to TR.
Linear Mode
