First its an est. tank (125 gal ) with ammo 0 (API)nitrite 0 nitrates 20(nutrafin) , weekly 30% water change with gravel vac ( python) Gh 20 (1+1 drop) kh >20( 1 drop chage to yellow) with a nutrafin hardness test . When I check my ph with API test I get 6.4 when I test with nutrafin test I get 5.5 , my tap water tests 6.8 , 5.5 respectively . All tests are liquid regent . I bought the nutrafin test as it was wide range and I wanted to make sure the API was not just bottoming on the range (6.0 ) . All tests are ok by the date on packaging , anyone ever have this happen.