Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
First on the left (bottom of bottle, I think)
GH. This is a measure of Calcium and Magnesium. The purple color seems like it is somewhere between 60- 120ppm, but on my monitor the bottle has blue tones, the tab on the strip looks purple.
KH. This is a measure of Carbonates and Bicarbonates. The pale-sea-green looks like it is in the mid-range of this test. I would call it 80ppm.
pH. This is a way of expressing how many H+ ions there are compared to OH- ions. I would read this as 7.0 or maybe a shade higher. Not quite to 7.5, though. Very slightly alkaline. (7.0 is neutral, lower than 7.0 is acidic)
NO2. Nitrite. This is toxic to the fish. Good, clean zero.
NO3. Nitrate. This is good for plants, not so good for fish. I am not sure if this is showing 20ppm. Light may not be right. 20 ppm is as high as I let my tanks get. I generally keep them between 5-10 ppm to keep the plants growing.
If you compared all these colored tabs at the correct timing for each, and used a good light (I usually stand near a window for bright but not direct sunlight) you may be able to fine tune the reading.
If these results are good or bad depends on the fish you want to keep.
GH and KH under 100 is generally good for most of the soft water fish like Tetras, Barbs, Cories, Loaches, Danios and many others.
GH and KH over 150 is generally good for most of the hardwater fish like Guppies, Mollies, Platies, many Rainbow fish, and the fish from the Rift Lakes of Africa.
If the KH is high, then the pH is usually high, and hard to change.
If the KH is low then the pH will be easy to change, and usually low, though other things in the water can make the pH high even if the KH is low.
Seeing no NO2, but yes NO3 suggests to me that the tank has completed its nitrogen cycle, and has enough bacteria for the current fish population. Test the ammonia, too, to be more sure of this.
Also, positive NO3 can be from fertilizers and have nothing to do with beneficial bacteria.
Bump: See- mattinmd and I are seeing things a bit differently- may be photo quality, monitor, test strip problem...