Hi, I started using these about 6 months ago and I love them. I use the ones called Quick Dip by Jungle. You can test your nitrate and nitrite with one strip, amonia with another, hardness with another, and ph with another. Just make sure that you don't reach into the bottle with damp fingers to get them out as moisture will damage the strips. I love them because I can find out in seconds everything that I need to know. I used to dread testing the water with the liquid vials where you had to add and count drops, try to match the color, and spend a lot of time. I think these are about as accurate for me as with the vials because I was always having to guess what color the liquid in the vial matched anyway. I guess they cost a little more.....only down side for me. Lesley