What's your favorite test kit ?

[magnosis]

I'm pretty sure my API test kit is bad, at least the NO3 (consistently reads 0 ppm for the last 6+ months whereas the algae in my tank seem to tell otherwise)
Since this came in a kit (PH,NO2,NO3,NH3) I'm not very confident that the other reagents are still good either, and I don't have reference solutions to verify their accuracy.

I also have a Hagen KH test kit that is inconsistent with an API KH test kit bought at the same time (both their expiry date was years ahead)

So, I need a new test kit.  Yes, I could do without, but running to Micro-B for a full analysis every 6 months is way more expensive than buying my own testing equipment.

I read a lot of positive reviews on the Salifert line.  Are they worth the extra cost ?
I'm also considering electronic meters, especially a PH one as I'm not entirely confident in the reagent used in my drop checker :/  I'm also bad at telling the difference between green-darkish-blue and greener-less-pale-blue and darker-green-but-more-blue-than-the-other-blue 


What is your personal favorite kit ? API ? Hagen ? Salifert ? Other ?


Also, a question from newbieland:  what is a TDS meter used for ?   OK I get it that it measures the total amount of dissolved solids,  but what's the point ?  Isn't it important to know what solids are dissolved in the water, vs just the total amount of ?

[FocusFin]

It depends on what I'm testing for but I like Salifert for Nitrates. On the other hand I don't like Salifert for Magnesium, the test calls for 4 drops of solution but the dropper is very sloppy so that as soon as you turn it over it squirts out. This has ruined a number of tests for me.

I was using Seachem for calcium but the powder got hard even though it was in a dry place so I instead bought an Elos calcium kit and am happy with it. I still use API for KH and haven't had a problem.

TDS meter is used to measure disolved solids in your RO/RODI water. Normal tap water can measure 100s of ppm whereas RO will measure maybe 10 and RODI 0ppm