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Types of Test Kits: Which one is Right for You?

  • Marine Depot
  • Oct 29, 2020

Testing your aquarium is one of the fundamental practices required to maintain a stable aquatic environment. Water testing allows you to see how well your aquarium is functioning. New aquarists often associate aquarium testing with problems like high ammonia and nitrite, but testing is for more than new tank start-ups. As your skill and aquarium experience increases, so will your testing ability. You’ll be able to spot subtle trends in parameters like calcium, alkalinity, iron and more. Testing gives you the ability to fine-tune your aquarium for optimal health and beauty. There are three types of test kits available for aquarists. We’ll explore each one and discuss how they fit into your aquarium care program.

Liquid Test Kits

Example of a Red Sea liquid titration test kit for major reef elements
Red Sea Multi Test Kit

Just about everyone is familiar with liquid type of test kits. These kits were developed for hobbyist use by simplifying established analytical test methods. Most of today’s test kits are “colorimetric”, meaning the test result forms a color in a test tube. The color shade or intensity corresponds to the level of the substance being tested. You match the color in the test tube to a color chart or wheel. The closest match is selected as the test result. A variation on this is the titration method. A chemical is added, drop by drop, to a water sample. When a specified color appears, the test is complete. Alkalinity test kits often use titration. The number of drops or amount of reagent added corresponds to the level of KH in your water.

Maximizing Accuracy with Liquid Test Kits

Liquid test kits are the most popular style of aquarium kit. They’re also widely used by environmental scientists for field work, in commercial aquaculture and by universities.  The kits are easy to use and provide results very quickly. Accuracy of colorimetric test kits depends on following the directions. For example, if a nitrate kit requires shaking a reagent bottle for one minute before adding drops to the test tube, don’t expect accurate or consistent results if you don’t follow the instructions. Lighting matters. Matching the test tube to the color chart is much easier under natural daylight conditions. Don’t try to match the colors near reef lighting or incandescent bulbs.

How Accurate Are Liquid Types of Test Kits?

There’s a lot of debate about which test kits are “the best.” Most aquarist’s conclusions are based on comparing two test kits on their tank’s water. Take phosphate testing for example. Whichever kit gives the aquarist the level they expect or desire is deemed “best.” This type of comparison is unreliable because the actual level of phosphate is unknown. Both kits could be wrong. Another misconception is that kits that cost more are more accurate. Here’s an example of the correct way to evaluate test kits.  We’ll use nitrate kits for this example. Water samples are prepared with nitrate levels 0, 0.25, 0.5 and  1.0 ppm. A panel of testers with no knowledge of the actual nitrate levels perform the nitrate test and write down the results. After all the tests have been completed, the results are compared to the actual nitrate levels. The most accurate and consistent test kits rise to the top of the list. This type of evaluation has been performed many times in a lab setting. Here are few key observations:

  1. Price is not always an indicator of quality and accurate result
  2. Following the instructions is critical for consistent results
  3. Expired reagents lead to inaccurate results
  4. Slight color differences (example: .1 ppm vs .2 ppm) are very difficult to accurately detect

Aquarists will always debate which kit is the best but the takeaway from these studies is that many test kits provide consistent and accurate results. Liquid test kits are very good for tracking trends and making adjustments basic water parameters and even trace elements like strontium and iron.

Electronic Types of Test Kits: Removing the Human Factor

Example of electronic test kits for major elements and salinity
Hanna Instruments Professional Reef Test Kit – Version 2

Colorimetric testing has one weakness. It depends on our eyes to accurately detect subtle shades of color. The truth is, our eyes and brain cannot consistently differentiate the slight changes in color that form in the test tube. The way to eliminate the human factor is to have a machine read the color. A device called a colorimeter evaluates the color and calculates the test result. Colorimeters are the next step up in water testing. A professional multi-parameter colorimeter can cost over $1000. But there’s good news. Hanna Instruments offers affordable single-parameter colorimeters that make it easy for aquarists to improve their at-home testing. These hand-held “Checker” colorimeters are calibrated to test individual substances important to aquarists. The Ultra-Low Range Phosphate Checker HC has a range of 0 to 0.9 ppm with a resolution of 0.01 ppm. This type of low-range testing is impossible using your eyes. The Hanna Checker colorimeters open up a new level of testing for freshwater and reef aquarists. There’s even a Professional Reef Test Kit that includes Checkers for phosphate, alkalinity and calcium, and includes a digital salinity meter.

ICP Types of Test Kits: The Gold Standard

example of mail-in test kits
ICP Water Analysis, Triton Labs Water Analysis, ATI Lab Water Analysis

Not long ago the only way to know the elemental make-up of your reef tank’s water was to have a friend at a lab or university. Analytical-grade testing for individual elements like sodium, iodine and other elements requires specialized equipment calibrated for testing seawater. This was unavailable to most hobbyists. That’s all changed now that Triton Labs and ATI offer ICP-OES tests. Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) is an advanced analysis technique used to identify and quantify individual elements in a water sample. ICP test kits are easy to use. Just fill the vials with a water sample and send it to the lab. The lab will test it and provide the results on an interactive website. The report will explain what the results mean and how to make corrections. You can even store multiple tests to track changes over time.

So which type of these test kits is right for you?

Liquid aquarium test kits have helped millions of aquarists maintain healthy freshwater and reef aquariums for over 50 years. There are more test kit choices than ever, especially for reef testing. If you have difficulty discerning test results or just want to get more consistent results, the Hanna Checker is the way to go. ICP testing will give you a clear snapshot of your reef’s elemental water chemistry. Some aquarists test once or twice a year. Others test monthly. It’s a great way to see if your tank has a deficiency or build-up of the major and minor seawater elements.

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