Test Kit Question

[ReefPony]

So, I used up all of my Salifert Nitrate test kit and my lfs was out of the Salifert kit but the owner suggested the Red Sea Pro as a good enough alternative.

My nitrates are and have been high but I'm starting to wonder if I'm doing something wrong with the Red Sea test kit.

For the high range test, the instructions say to use 15ml of RODI water and 1ml of tank water. When I do this, the levels show between 42 and 64 (multiply the reading by 16, apparently) ppm and have been showing that through 2 water changes, both of which were 33% of the tank water volume.

I sanity checked my kit twice tonight. Once with 16ml of RODI water and once with a fresh batch of saltwater that is mixing for my water change tomorrow.

The test with RODI water only showed nitrates of almost 1ppm but the test with freshly made saltwater (same water!) showed almost 0ppm.

Am I just imagining things or is using fresh RODI water to dilute the tank sample causing the test to read higher? Anyone else have any experience with this?

 

[MinnFish]

Are you shaking bottle "A" for 30 seconds and adding the drops quickly after shaking. This is very important to do. And shaking for 15 seconds after adding "B" and the same for "C".

 

[ReefPony]

Are you shaking bottle "A" for 30 seconds and adding the drops quickly after shaking. This is very important to do. And shaking for 15 seconds after adding "B" and the same for "C".

Its instructions don't indicate to shake Bottle A but I always give it a shake before opening it.

The instructions for the Pro kit just say 5 drops of A, shake for 15 seconds, 1 scoop of B, shake for 1 minute, 1 scoop of C, shake for 15 seconds, and wait for 9 minutes before comparing.

 

[ReefPony]

Interesting update. I did a 3rd test but this time I used 15ml of my freshly made saltwater and 1ml of tank water (the high range procedure but using saltwater instead of RO water). After following the procedure meticulously (like, reading the instructions as I did it) the test read somewhere between 16 and 32 ppm of nitrates.

Definitely makes me wonder if, despite their instructions, non-salt RODI water throws the test kit off when doing the high range test.