If you want to make your saltwater at home (which is cheaper and more reliable in the long run), you'll want to invest in a Reverse Osmosis DeIonizing (RODI
) unit as well as a refractometer (recommended) or hydrometer and of course salt mix. The RODI
unit can be plumbed into the house or you can get a portable unit you hook up whenever you need to make water.
With all but the most sensitive of freshwater fish, tapwater with a dechlorinator added is generally OK. It would generally be fine for saltwater fish, too, but there is a lot of trace compounds in tapwater that a dechlorinator does absolutely nothing for and may not be good for invertebrates including coral. It also ends up being fertilizer for algae which seems to grow WAY faster in saltwater. (Just skim the forums for people fighting hair algae or cyanobacteria, and you'll see what I mean.) The RODI
strips your tapwater off all of that so you have actually pure water to start your salt mix.
The hydrometer or refractometer measure the concentration of salt in the water. (The more salt in a given body of water, the more dense it is.) To make saltwater, you take approximately 1/2 cup of salt mix per gallon of RODI
, measure the specific gravity with the hydrometer or refractometer and add more salt or freshwater as necessary to adjust to a specifc gravity of 1.026.