Here are some of the most important test kits that every fish keeper should have:
Ammonia test kit. It may be used to monitor the nitrogen cycle, so you will know if the first phase (rise of ammonia level) has taken place. Testing the water’s ammonia is also important when unexplained fish deaths occurred.
Ammonia concentration is measured in ppm. As low as 0.2ppm can already cause rapid fish deaths while as much as 0.02ppm is tolerable, though stressful, for fishes. The test kit cannot read that low ppm. So if it has sensed ammonia in water, its level must be lethal. Just don’t use this kit after using Amquel, an ammonia-neutralizing additive, because it gives false reading.
Nitrite test kit. Unlike an ammonia test kit, the nitrite test kit is only useful for the nitrogen cycle. If it got some traces of nitrite, the tank is probably on the second phase. Nitrite is also a fish-killer, but not as deadly as ammonia. If your fishes survived ammonia, they would probably survive nitrite, too. A 0.5ppm is still tolerable but a 10ppm nitrite concentration can be deadly.
Nitrate test kit. At least 50ppm nitrate concentration is considered lethal for fishes. If the kit read that much nitrate, then have a partial water change immediately. Nitrate test kits are typically useful after the nitrogen cycle. Using this kit during the cycle will only give false reading since this kit reads the nitrite and nitrate combined.
pH test kit. The level of water’s acidity is measured with pH. This kit becomes necessary to know whether the water’s pH is still stable. Adding tank decorations disturb the water’s pH. In this case, pH check is needed to make sure that the water is still ideal for the fishes.
General Hardness kit. This kit is used to determine the water’s exact hardness level. Having one is okay but it’s not as necessary as the mentioned kits above. It’s already enough to know whether your water is hard or soft, and you don’t need a kit to know that. Simply ask the local water utility.
Carbonated Hardness kit. Like the GH kit, this one is not really necessary. It’s easy to know whether the CH level is high enough if the water’s pH is stable. Get this kit if you plan to tame plants and inject them with carbon dioxide. Have this one also in case you need to modify the water’s pH level.
Beginner fish keepers will find these kits highly important for familiarizing water chemistry. The need for these kits will lessen as you become an experienced fish keeper. For now, it’s good that you know that there are kits used to measure the important elements that compose your tank’s water.