Water Guide
There are several fundamental aspects of water that are considered to be of general importance. This guide is a brief summary of those parameters and common methods of testing their values.
pH
What is pH?
The pH of your water is one of the most commonly tested parameters. The pH indicates how acidic or basic your water is. As a baseline, a pH value of 7.0 means neutral pH (distilled water). Anything above 7.0 indicates a basic environment (such as ammonia) and anything below 7.0 is acidic (such as vinegar or orange juice). Technically pH is defined as:
pH = -log[H+]
This formula reads: pH is equal to the negative logarithm of the concentration of hydrogen cations (protons). Because pH is based on a logarithmic scale, each increase or decrease in one pH unit signifies a 10-fold increase or decrease, respectively, in the concentration of protons in solution. Therefore, small changes in pH values actually indicate large changes in the concentration of the acid or base in solution.
What are the methods for measuring pH?
There are several methods of measuring pH. They are LivepH, the solution-based method, the dip-strip, and an electronic meter.
LivepH is a brand new product developed by AquaStasis Corporation that was developed after months of scientific research, resulting in a device that returns accurate pH values in a continuous fashion, at an economical price. The main advantage of LivepH is that you can constantly monitor your pH without having to do anything but simply glance at your meter.
The solution-based method is accurate and inexpensive, making it a popular option. The drawback to this method is that it requires the user to perform several steps that can seem like doing a chemistry experiment! Also, the color of the solution is often hard to match to a printed color chart.
The dip-strips are becoming more popular because they are convenient. However, the strips are non-reusable, expensive, and rarely used by professionals because many believe they return inaccurate results.
Electronic pH meters are generally the most accurate means to measure pH values and common for applications that demand the highest accuracy available.
Alkalinity
What is Alkalinity?
Alkalinity is the sum of all the bases (compounds in water that react with acid to create neutral compounds) in the water sample. Typically, the major contributors to alkalinity are from carbonate (CO32-), bicarbonate (HCO3-), or hydroxide (OH-), and most measurements are intended to reflect the amount of these ions in solution. However, there may be contributions from other bases in the water sample, such as borates, phosphates, or silicates (this is why it’s called total alkalinity).
The amount of carbonate and bicarbonate in your water will determine how well your water is buffered against rapid changes in pH (in other words, how well your water can resist large changes in pH).
How do I measure alkalinity?
The most accurate way to measure alkalinity is using a titration method. A titration is a procedure in which a certain number of drops of one solution are added to your sample to produce a color change. The number of drops then corresponds to some number that represents the alkalinity. The test kits that use this method are always going to be the most accurate. Test strips will give you a basic idea of the alkalinity (or total alkalinity…or carbonate hardness) but should not be used if you require more specific values.
Hardness
What is Hardness?
Hardness, or general hardness (both terms are used interchangeably), is inherently related to the alkalinity of your water. Hardness is usually considered a measure of the magnesium and calcium concentrations given in calcium carbonate (mg CaCO3/L). Actually, when the hardness value is greater than the alkalinity value, then the alkalinity is considered “carbonate hardness.” The difference between the “carbonate hardness” and the “hardness” value is called the “non-carbonate” hardness. Here’s a diagram to better illustrate:
If the hardness is less than the alkalinity, then hardness is just equal to the carbonate hardness and there is no non-carbonate hardness:
How do I measure hardness?
Typically, hardness is accurately measured in a similar way to alkalinity, using a titration method. Alternatively, dip-strips will give you a general idea of whether your water is soft, hard, or somewhere in the middle, but not a specific reading.
Ammonia/Nitrite/Nitrate
What are these things and why are they important?
The element nitrogen is abundant in nature. Ammonia, nitrite, and nitrate are the three most common forms of this element found in aquariums. Unfortunately, ammonia and nitrite are very toxic to many organisms. The nitrogen cycle refers to the conversion of ammonia to nitrite and finally to nitrate by bacteria.
How do I test ammonia/nitrite/nitrate levels?
Like the other compounds in your water, testing these things usually requires the user to perform a little chemistry experiment in which some drops of a solution are added to your sample and then you need to compare the color to a reference chart. Be especially careful with the ammonia test solution as it probably contains some mercury, which can be poisonous. Although the test solutions may seem to be a hassle, they will provide more reliable results as compared to the test strips.
One last thing about testing for these compounds. Many kits will test for N-NH3, N-NO2-, and N-NO3-. These kits are using units of nitrogen, not units of the specific chemical you want to find out about. To convert the units of nitrogen into the units of each specific chemical, multiply the nitrogen values by 1.3 to calculate the level of ammonia, 3.3 to calculate the level of nitrite, and 4.4, to calculate the level of nitrate.
Note: This report was compiled by Roni Kopelman, Ph.D. (organic chemistry). References used include Standard Methods for the Examination of Water and Wastewater, a joint publication of the American Public Health Association (APHA), American Water Works Association (AWWA), and the Water Environment Federation (WEF).