StringerBell wrote:

Do you need to mix salt into tap-water to check the test? Or do ammonia
tests work for both Salt and Fresh Water?

I don't test for ammonia, but I think it highly unlikely that your tap water is
of such poor quality that it has ammonia in it. According to the Hagen web site,
however, they sell different ammonia tests for fresh water than for salt. If you
wanted to test your tap water with a marine kit, you could test water that you
mix up for a water change before adding it to the tank. The nitrite, nitrate,
and phosphate test kits work for both fresh and salt water.

George Patterson
All successes in conservation are temporary. All defeats are permanent.