well i assume my levels are fine because none of my snaisl or crabs have ever died..but i supose they are hardy, and my shrimp didn't die it got sucked to a filter intake and couldn't get free, so ya i knwo i need tests i have nitrite, nitrate, copper, and PH and all those have remained constant for awhile. ya i knwno 7 montsh is along tiem with no fish but i want to be sure that everything is right for my first fishies