Aquarium Lab NT Labs Multi water test kit
 
This is a great all round test kit covering the most often used tests. It is a liquid reagent kit which offers more accurate results. 
 
Included in the kit:
NH4 Ammonia
NO2 Nitrite
NO3 Nitrate
pH 6-9
General Hardness
Carbonate Hardness
 
There are up to 200 tests in total. There is also an easy to follow guide and colour chart. With instructions of what to do if the results are not as good as they should be. 
 
Ongoing you can order individual tests of your most used tests.