Basic Testing Needs

[bertoni]

When setting up a tank, testing ammonia, SG, and temperature are critical. A lot of thermometers in the aquarium trade seem to be rather inaccurate, so finding a decent one is worth a bit of effort. Calibrated units for photography cost about $20, and a glass NIST unit is about $50. For measuring SG, a refractometer and some calibration fluid work very well. Some people prefer a conductivity meter, which is more flexible and more expensive. Hydrometers can be made to work, but refractometers tend to be more reliable with less effort. In addition, floating hydrometers can make testing SG during acclimation impossible.

A pH meter can be very useful, mostly for stony corals, and better than a kit in terms of accuracy, ease of reading, and flexibility, but one or the other should always be on hand. If you get a meter, one that has resolution down to +/- 0.01 units is useful to have. The last digit on a pH meter generally is noise, and so a unit that's good down only to 0.1 units has a fairly coarse resolution. For example, a reading of 8.0 should be interpreted as somewhere in the range 7.9 to 8.1. Any unit should take at least pH 7 and pH 10 calibration solutions, which you'll also have to get.

Calcium, magnesium, and alkalinity are consumed by stony corals and coralline algae, and usually bear watching. For a fish-only system in which coralline algae growth isn't wanted, calcium and magnesium kits are optional, but alkalinity also helps maintain pH, so watching it can be useful.

Nitrate and phosphate kits are useful when growing stony corals. Phosphate can interfere directly with stony coral growth, and nitrate causes certain problems, as well. Nitrite is useful sometimes when a tank is showing a large amount of nitrate, since nitrite can confuse nitrate test kits. Nitrate and phosphate kits tend to be useless when dealing with algal pests, but many people recommend testing anyway. Very high levels of nitrate (over 400 ppm or so) might cause problems for fish, so some people recommend testing this parameter even for tanks without coral

Some people like to test nitrite and nitrate when curing live rock, too, but nitrite and nitrate can be ignored until stony corals are going into the system. Also, being able to test these parameters tends to cause people to obsess about numbers and trends that have little, if any, meaning.

Basic measuring needs needed for all marine tanks:

1. ammonia
2. SG
3. temperature
4. alkalinity

Kits for reef tanks with stony corals or coralline:

1. calcium
2. magnesium

Kits sometimes useful for trouble-shooting or preparing reef tanks with stony corals or coralline:

1. phosphate
2. nitrate
3. nitrite
4. pH

This article covers all the water parameters in more detail.