Get the most from your test kits.

[fish_doc]

Test Kits: How to Get the Most From Them

by Timothy A. Hovanec, Ph.D.
The benefits and utility of aquarium water test kits are, in my opinion, not fully appreciated by most hobbyists. But, paradoxically, over reliance by some hobbyists can lead to unnecessary, even potentially dangerous, micro management of the aquarium environment. This column deals with how, when and why to use water test kits.
Test kits are pre-packaged mini-chemistry sets that range from the easy to the moderately complex. They allow the user to determine a single water quality characteristic. There are test kits for almost every chemical or substance of concern to the fish hobbyist. The common kits include ammonia, nitrite, nitrate, pH, and phosphate (in one form). Others are alkalinity, hardness, and dissolved oxygen. Many are simple to use and are relatively accurate for their price and convenience. Others can get expensive and incorporate colorimeters or spectrophotometers to measure the concentration level of the substance in question as will be discussed.
The majority of test kits are colorimetric in nature. Colorimetric means that the water will change to a certain color if the chemical in question is present. Further, over a certain range, the intensity of the color is proportional to the amount of the chemical present, so the color will be darker as the concentration increases.
Most test kits operate by placing a small amount of aquarium water in a vial. Next a few drops (or some powder) of a chemical reagent are added to the sample and the solution mixed. After waiting a short time, other reagents are added in the same way for those test kits which require more than one reagent. After the final reagent is added and mixed, the sample is allowed to stand for a few minutes or so. At some point in the course of adding reagents or standing, the sample will change from colorless water to a colored liquid. The actual color varies with the test. For example, ortho-phosphate is usually blue, nitrite reddish-pink, and ammonia yellow-green. Therefore, for most tests, no color change in the sample after the allotted time means that the amount of chemical present is 0. To determine the concentration, the water color is compared to a range of colors on chart accompanying the test kit. Some kits use a paper chart, others use colored plastic and a few use colored water permanently sealed in vials. Match the color of the water sample to the one closest on the chart and read the corresponding value to get the concentration. When comparing the sample to the chart, hold it up against a white background and in good lighting to get correct values. This is an area that sometimes requires a little guess work by the hobbyist due to the subjective nature of the test.
Some hints for getting an accurate reading are: 1) always rinse the vial with the aquarium water a few times before filling it to the prescribed volume. This will ensure that there is no contamination from a previous sample. 2) Don't sample water from the aquarium surface, rather sample deeper water. Proteins and other substances may accumulate at the water surface and they can contaminant the sample. 3) Don't cover the top of the vial with your fingertip when shaking, as this can contaminate the sample leading to a false value and it is not safe for your finger. 4) The reagents should be added in the order stated in the instructions. 5) Work on a paper towel away from food and drink to minimize the chance of ingesting the chemicals. 6) Always wash your hands when finished. 7) Rinse the sample vials with clean water immediately after use so they do not build-up material. Also to get the best reading, the water sample should not be turbid or colored. If the aquarium is cloudy or dirty, try taking the sample from the exit of the filter. This water may be cleaner but still be representative of the chemistry.
The range of the values that tests kits can measure varies from manufacturer to manufacturer. Some kits measure a wide range but they are not very precise. This means, for instance, that the value can be read as either 1 or 2 parts per million (ppm), but not as 1.25 or 1.75 ppm. Others kits are rather precise but the range is small. For these types of kits, the highest value may be 1 ppm or less. The choice between these two types of kits depends upon your needs. The wide range kits give an indication of the presence or absence of the chemical while the smaller range kits can be used for semi-quantitative analysis.
The goal behind measuring the water is to get a value of the chemical compound. That value will have units of one form or another such as milligrams per liter (mg/L) or parts per million (ppm). It is important to be consistent with the units of measurement so you can easily compare values from one day to the next.
Further, test kits from different manufacturers may seemingly measure the same thing (i.e., ammonia), but they may present their results in different units or may actually measure slightly different forms of the compound. This may not be readily apparent unless the instructions are carefully read. This does not mean one test kit is inherently bad over another. Just make sure you know exactly what you are measuring.
This is a common problem with ammonia test kits, for instance. There are actually three "types" of ammonia that can be measured. These are 1) the ammonium salt or ionized ammonia commonly called ammonium (written NH4+); 2) un-ionized ammonia (written NH3); and 3) total ammonia which is the sum of the NH3 and NH4+. To add further confusion, the determined value can be based on one of three possible standards. The standards for ammonia can be based on either nitrogen (N), un-ionized ammonia (NH3) or the ionized ammonia (NH4+).
Most ammonia test kits measure total ammonia and base the value on nitrogen (kits that say this are measuring all the ammonia in both forms and the value is based on the nitrogen fraction of the ammonia). Un-ionized ammonia (NH3) is the toxic form of ammonia and its percent of the total ammonia varies with pH, salinity and temperature (with pH being the most important). Some test kits include the conversion table so you can determine the amount of NH3 present. This is nice for those who want this information, but it is best to strive for no ammonia of any form to be present in the water.
The values determined with most nitrite and nitrate test kits are based on nitrogen (so the abbreviation will look like NO2-N or NO3-N). A conversion factor is then given to calculate the amount of nitrite or nitrate ion. It doesn't really matter which form you use, just be consistent with the form. It is akin to measuring in inches or centimeters, the length is the same, it is the units that are different. Therefore, make sure you don't mix units. This can happen when you take a water sample into a store for a check. If their test kits are different than yours, the units and what they are measuring may be different. If the values from your own testing vary widely from the store's, check that you are comparing apples to apples.
The test kits that every hobbyists should have include ammonia, nitrite, and pH (plus salinity, which is necessary if you have marine fish). Nitrate, phosphate and chlorine are also good kits to have on-hand. For complete testing, include alkalinity, dissolved oxygen, carbon dioxide, and hardness. It is important to start a logbook, recording the values when you perform the tests. That way when you have problem you can have the water quality data right at hand. In fact, you may want to take it to the store with you.
A few manufacturers are now labeling the chemicals and reagents in their kits with expiration dates. Many substances have a definite shelf-life and use beyond this date can lead to erroneous results. If you have a kit that does not have an expiration date and it is over a year or two old, chances are the reagents are no longer good and should be disposed of properly. Standards are also available to check your kit. A standard is a solution with a known amount of the substances you're interested in measuring. The standard is used to check the accuracy of the test kit. If the standard is labeled 1 mg/L of total ammonia-nitrogen, your test should give that value when you perform the test.
Many test kits contain strong acids or bases, and some have toxic chemicals. Keep your kits away from children and pets. Do not keep them in the kitchen or under the aquarium where small hands can get them. Wash your hands after using the test kit and flush any disposal with lots of water.
Test kits are a basic tool for successful fishkeeping; you cannot tell the water quality without them. They tell not only where the water quality has been, but where it is going. Test kits are inexpensive insurance for the protection of your aquatic creatures. Take the time to read the instructions and know what you are measuring and discuss with your customers the importance of regular water testing. I suggest testing your water once a week with the three basic test kits (ammonia, nitrite and pH). If you have other kits, test the water every 2 to 4 weeks. Also test again after you do something to the system such as a large water change, filter cleaning, or stirring-up the gravel.
If the values are out of the ordinary (determined by comparing the current value to the historical values in your logbook), check the filtration system first. If it is working, then check in the tank for an accumulation of uneaten feed, or a dead fish or something else which could be causing the problem. Water quality values change on a daily, weekly and monthly schedule. The goal should be to look at long term trends.
The data from the test kits will tell you when the water needs changing, or the filter cleaning, or the amount of feed reduced. Used regularly, test kits can help you spot problems early, before they become catastrophic.

[fish_doc]

Kind of long but thought it might be helpful or educational to a few here.
Found it online.

[kristian18f]

Thanks for posting

[Cichlid Man]

Very useful FishDoc. Keep up the good work.