Hydrometers are a fairly simple and inexpensive means of obtaining salinity. Their greatest asset, however, is the high level of consistency they offer over time. The more dissolved solids in water, the slower light travels through it. Refractometers measure the change in the direction of light as it passes from air into water. Salinity and temperature both affect the index.
Refractometers use a scale to quantify the effect that dissolved solids in water have on light.
Using a refractometer is simple. It works with ambient light, and no batteries are required. Chlorinity Salinity is related to chlorinity, and this method calculates salinity based on the quantity of chloride ions in the sample. The chlorinity method uses titration with either a silver nitrate or mercuric nitrate solution. Some kits require conversion of chlorinity to salinity using a formula, while others incorporate the formula and give results directly as salinity.