Cons
- Multi-language instructions.
I get that these are sold worldwide and you want to make one universal instruction booklet but honestly it's a pain to go page by page and look for your little section for your language. The only plus is that when you have done it long enough you probably won't need the booklet unless to reference for corrections to the tests.

- Caps.
These do not seal firmly. You can't invert or shake these containers without the test liquid getting on your hand. Even if you wrap the top in a towel to prevent it from getting on your hands you are still absorbing the liquid. I don't know if this alters the test parameters but it doesn't scream accuracy.

- Hard to distinguish colors.
Do I have 0 ammonia or .25ppm ammonia? Sometimes it's incredibly difficult to distinguish because the increments in color are so close to one another that you almost have to guess.

- Doesn't include all the tests.
GH/KH test sold separately, and I'm sure there are others I'm missing. When it's called the "master" test kit, I would think it would have all the tests available. While I knew that it didn't include these tests I just want to make it known and this part doesn't reflect on my rating.

Pros

For the price you won't find another suitable kit and this is essential if you want a healthy aquarium, especially if you're just starting out where testing is important before adding livestock.
Cons
- Multi-language instructions. I get that these are sold worldwide and you want to make one universal instruction booklet but honestly it's a pain to go page by page and look for your little section for your language. The only plus is that when you have done it long enough you probably won't need the booklet unless to reference for corrections to the tests. - Caps. These do not seal firmly. You can't invert or shake these containers without the test liquid getting on your hand. Even if you wrap the top in a towel to prevent it from getting on your hands you are still absorbing the liquid. I don't know if this alters the test parameters but it doesn't scream accuracy. - Hard to distinguish colors. Do I have 0 ammonia or. 25ppm ammonia? Sometimes it's incredibly difficult to distinguish because the increments in color are so close to one another that you almost have to guess. - Doesn't include all the tests. GH/KH test sold separately, and I'm sure there are others I'm missing. When it's called the "master" test kit, I would think it would have all the tests available. While I knew that it didn't include these tests I just want to make it known and this part doesn't reflect on my rating. Pros

For the price you won't find another suitable kit and this is essential if you want a healthy aquarium, especially if you're just starting out where testing is important before adding livestock.