I have the old Nitrate Checker can I use its kit with the new HI782?

No, components from the HI781 are not compatible with the HI782.

You may be asking yourself, but they both test for marine nitrates, why would they have different components? This comes down to the chemistry needed to achieve accurate results.

Like with many colorimetric tests (tests that need a sample, chemicals to react with the sample, and then a noticeable color change that correlates with concentration), one single test will not necessarily be able to measure the entire range. Therefore, you may have i.e. a low range, mid-range, and high range checker. The sample preparation steps, the concentration of the chemicals, and the wavelength used to read the sample can all vary according to the method the checker is based on. We strive to give you the greatest accuracy possible at an economical price.