Jul 5, 2001
The Bottom Line What do you need?
If you are a hobbyist and have a small number of tanks - the standard kits from Tetra, Aquarium Pharmeceuticals etc. should serve you fine.
If you run many tanks [like me] you'll want to invest in meters.
For example, a test kit that has many different tests like pH, kH/gH [hardness], nitrite, nitrate etc. may run $25-$35 and last quite a while.
For an entry level pH meter you can find one for about $50 but the difference is night and day. Dip the meter into the water and instantly know the pH to within .01 - if you have a large number of tanks you can see how this would pay off - especially when doing water changes to match the new water with tank water conditions.
I use a Temperature meter, Hardness Meter and pH meter. I don't test for nitrates, nitrite, ammonia etc. as I do water changes frequently and maintain my filters and have never had a problem with water quality in my life but change a MINIMUM of 25% of the tanks volume per week [you can probably get away with 10% per week in a hobby tank - see my other opinions on water changing].