Which Kits?

For the planted tank, some test kits are essential: pH, KH, GH, and nitrate. KH is a measure of alkalinity, or the buffering capacity of the water; it tests the cabonate/bicarbonate ions. GH is a measure of hardness and is essentially the contributions of calcium and magnesium. pH, as your probably know, is a logarithmic scale used to measure the acidity of water. Call your local water department or check online for their lastest analysis of your tap water.

Other test kits that are helpful are Iron and Phosphate.

Some tests are more of a luxury or are needed only in particular cirumstances:
• Potassium – Potassium is difficult to measure and can safely be added to excess in our tanks anyway. (For the curious, potassium forms no colored salts and the only field-type tests available are based on turbidity, which is difficult to quantify by eye.)
• Oxygen – Needed only if you are curious or if your fish and plant loads are heavy and you think your morning oxygen level is too low (fish gasping at the surface). Tetra makes a fairly good, inexpensive O2 Kit; LaMotte a more expensive, very good one.
• GH – An advanced kit will breaks the hardness readings down into the Calcium and Magnesium components These kits usually let you measure both the total hardness and calcium hardness; you subtract the readings to get the magnesium hardness.
• CO2 – You usually determine your CO2 reading using the Krib chart with your KH and pH readings, however, peat and commercial buffers can make the chart inaccurate. With a CO2 kit and the chart, you can use any two of the three parameters to derive the third – a nice check of your test kits. I have found the LaMotte CO2 kit (mod.7297-DR) to be consistent with my chart-derived values.

A narrow-range pH kit makes chart-derived CO2 readings that much more reliable.
See Tom Barr's Recommended levels of specific nutrient to learn how much of a nutrient you want.
Some folks prefer to test less and rather learn to recognize Signs of Nutrient Deficiencies (by Chuck Gadd) to dose their fertilizers.
Often it's not essential to know the exact level of a nutrient, but simply to know if the level has gone up or down since your last reading.

Test Methods

• Colorimetric tests (color chart, comparator, color wheel or color cube) – After testing, you pick the closest match of your color to the reference colors on a paper chart – a set of sealed, liquid reference solutions – or colors on a plastic wheel, slide or cube.
• Titration – You add drops of reagent until you get a color change. The number of drops needed is used to get your reading. With some titration kits you add a liquid reagent from a graduated syringe and read the result directly from the syringe.
• Test Strips – You dip the strip in your sample and match the color to a chart. These are generally less accurate tests.
• Turbidity – (Potassium only). You measure (or compare) the cloudiness of your test solution
• Meters – pH can also be measured with a pH meter (see below).
• Pocket spectrometers – Some measure a specific element, others a large number ofof elements. They are very expensive and you still need to buy the reagents for each test nutrient. In fact, the chemistry of the tests is usually the same as that in our test kits. The spectrometer simply automates the reading of the test solution for more accurate, reliable results. They are aimed at the professional who tests water all day and not us "poor" hobbyists.

Accuracy – An accurate kit will give you readings that are close to the actual concentration of your test solution.

Convenience – Convenience is reflected in the difficulty of performing the test, the time you need to complete it, and the ease or difficulty of making the reading.A test that is not convenient might be messy to perform, require a long wait time, be difficult to read because the color never matches a reference color, or require you to perform a calculation to convert the reading to parts per million (ppm).

Cost – Consider not only the initial cost of the kit but also the cost of refills for just the reagents. Be sure to take into account the number of tests you get for a refill when comparing kits. A cheap kit that won't do the job just means you need still need to buy the better kit.

Checking your kit

If your kit is supposed to test down to zero (as most do), make sure you get a zero reading with distilled water (pH being an exception).

To check the accuracy, you need to make up a test solution of known concentration (some kits come with a stock of reference solution that you can test). See Chuck Gadd's Nitrate Calculator. Or you can test your tap water and compare the value to the most recent reading of your water dept. The latter isn't perfect, but does give you some feedback.

To check precision, make a few readings of the same tank sample. Make up a test solution with a high concentration of the test nutrient. This requires a tiny grain of a compound (like potassium nitrate) in a container of water. Then start diluting by one-half or one-third until you test at the top of your kit's range. Then start diluting by 1/4 and see if your readings reflect your dilutions.

For resolution, dilute by smaller amounts and see if you can detect the change.

About Accuracy and Precision

If you mount a firearm so it is in a fixed position perfectly aligned with the target, you can measure its accuracy and precision. Accuracy refers to the closeness to the true value, or position; precision refers to the closeness of repeated readings or tests to each other.

Test kits from Aquarium Pharmaceutical are fine for pH (6.0-7.6), GH and KH and are economical. I happen to find the color change of Tetra's GH kit easier to use over that of AP.

LaMotte and Hach makes excellent series of narrow-range pH kits. These come with a "comparator" which lets you compare your test sample with eight sealed, liquid references. You look through your sample and the references at a light source. Reading is easy, since you are comparing liquid to liquid and not liquid to paper. You can resolve easily to 0.1 pH unit, and even 0.05 with a good eye. If your online supplier doesn't carry their kits, you can order directly from LaMotte and Hach. They also have good phone tech support if you have questions regarding their kits. For a given parameter they usually make several kits which vary in test method (the chemistry of the test), comparison method (color cube, slid, wheel, comparator, etc), test range (narrow, broad, multiple) and price.

A pH meter is another way to track the pH of your tank.Meters are more expensive than test kits and you need to keep the probe calibrated and in working order.A good meters will give you about a 0.1 pH unit resolution.

Our Test Kits

Planted Tanks and the "Silent Cycle"

Ammonia and Nitrite kits are usually useful when cycling a tank. However, if your tank is heavily planted, the chances are you won't see an ammonia or nitrite spike if you track these parameters when cycling. In fact, the only indication that your tank has cycled may be the appearance of nitrates. Even then you may not get a reading: heavily planted tanks with a light to moderate fish load often test zero nitrates, since the plants take up some of the ammonia before the bacteria convert it, plus most plant species can back-convert both nitrite and nitrate to ammonia (ammonium). If you let a large plant load get established for a week or two in your new setup, it's usually safe start to add groups of fish in weekly increments, but testing for zero ammonia and nitrite first is always a good idea. Remember to put in some fish food while your plant are getting established so they and the beneficial bacteria have some nitrogenous waste for food. In addition to planting heavily, it's wise to start out with a nice percentage of stem plants, which, growing fast, consume more nutrients (fish waste). Once your tank is well-established and in balance, you can start to replace some of the stem plants with slower-growing, rooted ones (if you like).

Nitrate Monitoring

Once your tank is planted, let nitrate be a guide for water changes and nitrate addition. If your nitrates are running high (large fish load) you may need to increase the size/frequency of your water changes. But keep nitrates from going to zero by adding potassium nitrate. A good target range is 5–15 ppm. Tom Barr writes that about 1/4 teaspoon per 35 gallons of water will give you an increase of 6ppm of NO3 and about 4 ppm of K. See also Chuck Gadd's Nitrate Calculator. To monitor nitrate with accuracy and precision we need, we want a narrow-range nitrate kit that covers appromimately the 0–50 ppm range.