Beginner FAQ: Test Kits
There is a seemingly endless array of test kits for testing
everything from ammonia levels to phosphate levels. Does one really
need to buy them? The quick answer is no. It is quite possible to
have a healthy tank without ever buying a single test kit. However,
test kits are extremely useful at eliminating guesswork when something
goes wrong (e.g., fish appear stressed or die). In the following, we
describe the test kits that are most useful and the conditions under
which they are useful.
Which Are Useful?
- not cleaning the filter regularly (water can't flow through a clogged filter, where the nitrifying bacteria reside),
- naively adding fish medicines (antibiotics kill nitrifying bacteria (oops) as well as disease carrying ones),
- having too small a filter for the fish load, etc.
Ammonia levels are measured in ppm. At concentrations as low as .2-.5 ppm (for some fish), ammonia causes rapid death (consult the CYCLING SECTION for further details). Even at levels above 0.01-0.02 ppm, fish will be stressed. Common test kits don't register such low concentrations. Thus, test kits should NEVER detect ammonia in an established tank. If your test kit detects ANY ammonia, levels are too high and are stressing fish. Take corrective action immediately by changing water and identifying the source of the problem.
Warning: Amquel and other similar ``ammonia-neutralizing'' water additives are incompatible with most ammonia test kits. Water treated with Amquel will falsely test positive for ammonia, even when ammonia is not present. Test kits using the ``Nessler'' method are known to give false readings under such conditions.CYCLING SECTION). As in the case for ammonia, if your test kits detects nitrite, your biological filter is not working adequately. Once a tank has cycled, nitrite kits are pretty much useless. (If the bio filter in an established tank isn't working, both ammonia and nitrite levels will be elevated.)
Nitrite is an order of magnitude less toxic than ammonia. Thus, one common saying about tank cycling is: ``if your fish survive the ammonia spike, they'll probably survive the nitrite spike and the rest of the cycling process.'' However, even at levels above .5 ppm, fish become stressed. At 10-20 ppm, concentrations become lethal.
Nitrates become toxic to fish (and plants) at levels of 50-300 ppm, depending on the fish species. For fry, however, much lower concentrations become toxic.
Note: A nitrate test kit is only of limited value in determining whether the nitrogen cycle has completed. Most nitrate test kits actually convert nitrate to nitrite first, then test for the concentration of nitrite. That is, they actually measure the combined concentration of nitrite and nitrate. In an established tank, nitrite levels are essentially zero, and the kits do properly measure nitrate levels. While a tank is cycling, however, a nitrate kit can't tell you how much of the reading (if any) comes from nitrate rather than nitrite.
In some cases, tank decorations (e.g., driftwood) or gravel (e.g., made of coral, shells or limestone) change the pH of your water. For example, tank items may slowly leach ions into your tank's water, raising the GH and KH (and pH). With driftwood, it is not uncommon to have the wood slowly leach tannins that lower the pH.TAPWATER SECTION of this FAQ). call your water utility.
A KH kit is, however, indispensable to plant enthusiasts who use CO2 injection. It is also strongly recommended that you get one if you want to change the pH of your water, and it is a very useful diagnostic tool if you are experiencing pH stability problems.