Saltwater Testing

Water testing is a significant portion of the maintenance required to keep a saltwater aquarium. Saltwater fish require a delicate balance of salinity and pH levels, as well as trace levels of minerals such as calcium and iodine. Water testing is the only way to monitor the small environmental changes that can have enormous consequences for your fish.

Why test? Marine fish and invertebrates have very specific environmental needs. Whereas freshwater fish come from naturally fluctuating environments, the oceanic homes of marine fish are very stable. If an aquarium strays outside of those natural parameters, saltwater fish will not survive. Types of Tests The primary measurements in a saltwater aquarium are salinity and pH. Aquarium salinity is measured in relation to water by PPT, or parts per thousand. Saltwater fish need a salinity level between 24 and 34 PPT.

The acidity of an aquarium is expressed by its pH level. Optimum pH for a saltwater aquarium is between 8.0 and 8.4, specifically 8.2. A pH of 7.8 will make saltwater fish vulnerable to infection, and a pH below 7.6 will kill them. Rapid changes in pH are also detrimental and should not exceed more than 0.2 in a single day.

Other types of tests are also necessary for a healthy saltwater aquarium. High ammonia levels indicate that biological filtration is not occurring properly. An aquarium's calcium level will drop as invertebrates use available calcium. High nitrate levels foster excessive algae growth and are indicative of poor water quality.

Testing Equipment
Hydrometers and refractometers are the devices used to measure salinity levels in saltwater aquariums. Hydrometers are the commoner of the two and can be purchased for under $10. The most popular hydrometer is called a swing arm hydrometer. Refractometers are much more expensive than hydrometers (anywhere from $50 to $80), but they're extremely accurate and well worth the cost if you're setting up a costly reef tank.

Ammonia, nitrite, nitrate, copper, phosphate, silica, pH, and calcium levels can be determined by using saltwater test kits. Individual test kits sell for around $10 to $15. All-in-one saltwater aquarium test kits will cost about $40 or less.