RyanTheFishGuy64 said:
Tetra 6 in 1 is good for beginners.
I use this and they arent dead yet
The Tetra 6-in-1 does NOT include an ammonia test. This fact alone means that however cheap they are, they are not worth the money. I have to say that I, along with most experienced aquarists, consider ammonia to be an essential test to have at one's disposal. Ammonia in the water is the first sign that something is not right with the biological filtration - so you need to be able to test for it.
There are other strip tests which do include ammonia. Some people argue that in an established aquarium, these are accurate enough to tell you if you have a problem, on the basis that any ammonia and/or nitrite is too much, so if you get any reading at all, you know you have a problem. Therefore, one uses strips when you aren't expecting a problem, and switch to liquid when a greater need for accuracy is needed. I can see the logic of this, however I have heard stories of people seeing false positive results and therefore doing all sorts of emergency water changes and the like which turned out not to be necessary. I guess with that, you pay your money, and you make your choice.
Personally, I have always subscribed to the point of view that I don't want to risk false positive results, so have always used liquid tests. I started off with the Nutrafin master kit (which is expensive) and indeed am still using the pH and nitrate tests from this kit. Many people swear by the API, and if you know the caveats with the ammonia and nitrate tests, they will do a good job at a reasonable price.
You could always buy the ammonia, nitrite and nitrate tests individually, which will save you a little by not having to buy the pH KH and GH tests in the API Master, but not a huge amount.