Difference between low range and high range nitrate test

[Diver86]

can someone tell me what the difference is?

[Mpfaff77]

I would think it varies to each test. What kit r u using?

Normally you start with the low range test and If the color change is darker than the highest low range then you move to the High range test to get the correct reading. Ideally you want to stay in low range.

For instance my low range on Red Sea kit for phosphates goes to .64ppm. If it is my result is darker than the color for .64ppm I have to dilute my water with some RO water and retest

Hope that helps.

[Fizz71]

I'm going to assume you meant on a conceptual basis...if not Mpfaff7 already answered it. I'm also going to use numbers I pull out of my butt rather than off a real kit since I'm only talking concept...

When dealing with FO and even FOWLR your tank can tolerate higher nitrates in the 30s and 40s with no issues, but folks with reefs try to keep them below .5 (note the decimal) since our corals don't like them. Because of how the colors are SOOO close together if I use a high range nitrate test kit it really won't give a reef guy like me the 0 to .5 details I want...it will just be really d*mn low (under 10). So I need the low range kit to see the 0 to .5 level.

Now if the low range goes off the charts I need to break out the high range to see how bad it is, but my goals is never to NEED the high range. One might also use the high range when cycling.

I like the test kits that measure both with the same kit; you're basically just diluting the sample for the low range.