Just a suggestion when posting pictures of the test viles for your water prop a piece of A4 against a wall in a well lit area and put the viles up against that, the card with the colour chart can be placed in front of them laying down. This will give us the best possible indication of the colours of the test viles even with colour variations due to different computer monitors.
Also be sure to shake the viles really well after adding the reactive chemical and wait the full amount of time before settling on the final reading.
If you are going to test both your tap water and tank water straight after each other I would give the viles a good rinse out between each source test and dry the viles as best you can with a lint free paper towel or other material. This should reduce the chance of any residual tested water interfering with the next test.
Also be sure to shake the viles really well after adding the reactive chemical and wait the full amount of time before settling on the final reading.
If you are going to test both your tap water and tank water straight after each other I would give the viles a good rinse out between each source test and dry the viles as best you can with a lint free paper towel or other material. This should reduce the chance of any residual tested water interfering with the next test.
