A Summary of Water Quality Tests and Recommended Use
Parameter | Purpose | Freshwater | Saltwater | Required? | Frequency | |
|---|---|---|---|---|---|---|
Dissolved oxygen1 | Determines concentration and percent saturation of oxygen gas in solution | Yes | Yes | Required | Daily | |
Temperature | Many fish are susceptible to infectious disease outside a narrow temperature range | Yes | Yes | Required | Daily | |
Salinity | Measures the salinity of water which is critical for marine systems | Noa | Yes | Required | Daily | |
pH | Determines acidity or alkalinity of the water; scale of 1–14 | Yes | Yes | Required | Daily | |
Carbon dioxide | Measures concentration of carbon dioxide gas in solution | Yes | Yes | Recommended | Monthly, or whenever fish ar sick | |
Total ammonia nitrogen (TAN) | Measures combined ammonia (NH3) and ammonium (NH4+); unionized ammonia (NH3) is calculated | Yes | Yes | Required | Weeklyb | |
Nitrite-nitrogen | Measures nitrite-nitrogen; nitrite (NO2-) causes methemoglobinemia (especially in freshwater fishes) | Yes | Yes | Required | Weeklyb | |
Nitrate-nitrogen | Nitrate (NO3-) accumulates in systems due to less water change; contributes to goiter; may be harmful to some fish at high concentrations; harmful to some invertebrates | No | Yes | Recommended | As needed | |
Total alkalinity | Measures buffering capacity; primarily carbonates; required for biological filtration; essential for calculation of copper sulfate treatment in freshwater systems | Yes | Yes | Required | Monthlyc | |
Total hardness | Measures divalent earth minerals; primarily calcium and magnesium | Yes | No | Recommended | Monthly | |
Chlorine, free | Measures free chlorine in water from municipal water treatment | Yes | Yes | Recommended | As needed | |
Chlorine, total | Measures total chlorine (free chlorine + chloramine) from municipal water treatment | Yes | Yes | Recommended | As needed | |
Copper ion (free and total) | Measures free copper ion (Cu2+) in solution; essential for titrating copper treatments in marine systems | Nod | Yes | Required | As needed | |
Saturometer | Measures total gas pressure; used to calculate percent saturation of nitrogen gas for confirmation of supersaturation ("gas bubble disease") | Yes | Yes | Optional | As needed | |
Hydrogen sulfide | Measures hydrogen sulfide in solution (most commonly from well water source); "rotten egg" smell for those who can smell it | Yes | Yes | Optional | As needed | |
Iron, total (Fe) | Measures total iron in solution (most commonly from well water source) | Yes | Yes | Optional | As needed | |
aSalt is frequently added to freshwater systems in concentrations up to 5 g/L; monitoring is recommended in these situations. | ||||||
bIf ammonia or nitrite are detectable, the frequency of monitoring should be increased to daily. Daily monitoring is also recommended during the startup phase of a new biological filter or recirculating system. | ||||||
cIf pH of the system water is below pH of source water, alkalinity should be checked. | ||||||
dThe copper ion test kit will work in freshwater systems in which there is a need to measure free copper ion, such as a system in which the water supply is from copper pipes. It is not routinely used in management of freshwater systems but is essential for managing copper treatments in marine systems. | ||||||