What is the best reading on the Hydrometer for Salt level in 135gallon Fresh water tank? Is this the best way to measure salt levels in a fresh water tank?
unless your tank is pure h20 with no soluble compounds in it, it wont be zero. However to your naked eye it should appear to read zero.
freshwater is considered 1.000sg to 1.001 sg. Once you hit 1.002sg its considered light brackish.