Water testing equipment and meters measure water quality in both professional and academic environments. Colorimeters test concentration levels of chemicals and heavy metals. Conductivity meters help measure the capacity of ions to carry electrical currents in an aqueous solution. Dissolved oxygen meters help measure the amount of gaseous oxygen in water. Electrodes and probes test water in the lab or the field for ions, solvents, pH, heavy metals, and sulfites. Hydrometers help determine standard parameters and a variety of special applications for a wide range of liquids. ORP meters measure the cleanliness of water and its ability to break down contaminants. Salinity meters measure the amount of alkali metal salts or magnesium salts in aquaculture, aquariums.