Aquarium Water Testing for Beginners

An idea that I have heard often within the reef community is that you are not caring for corals or fish, but rather you are caring for the water that these organisms live in day to day. When caring for this water that your fish and corals are living in, you need to test it in order to understand issues that are happening in the tank or to possibly know why things are growing successfully and fish are living happily. There are many ways to test water and some are certainly more accurate and some are more expensive as well. Testing can be the difference between a beautiful vibrant reef system and a crummy glass box full of water.

Why Testing is Necessary

Testing water parameters is an essential part of reef keeping. It allows an aquarist to determine the cause for specific problems occurring in their tank. It can also tell an aquarist that everything is stable. You may have a water change schedule, but testing can tell you that you need to do an additional one. Also, by testing you can decide if you need certain additives. It will alert you of possible equipment failures. Without testing water parameters, all you can do is assume and guess, while you should be confident with what additives you are dosing or corals and fish you are adding to the tank.

Testing Methods

There are many different parameters to test for and different ways to test for these parameters. First, you need to determine what you need to test for. The most common parameters for a beginner to test for are ammonia, nitrites, nitrates, pH, phosphate, salinity, and temperature. As you advance in the hobby you will most likely also test for calcium, alkalinity, and magnesium. For this article, I will be focusing on the basic parameters.

The most common method of testing most of these parameters is using a test kit that can be bought at your local fish store or on online. Some of these test kits are great, while others are very inaccurate. A common mistake a beginner makes is using test strips. Test strips are not trustworthy as a method of testing, as there are many other factors that come into play when using these test strips.

If you are using an inaccurate routine of testing, you may get incorrect results, which is an issue because you may do things to the tank that are not needed or harmful. An example of this is using a hydrometer to test salinity. Hydrometers use density to measure the level of salinity or specific gravity and while they work, there are other factors that can cause incorrect results. Compared to a refractometer, hydrometers are also more fragile. The arm can get salt built around it, which will cause it to work improperly. On the other hand, refractometers are known to be more accurate, as they use refraction of light to measure salt levels. This is just one example of how different techniques can make a difference.

When it comes to measuring nutrient levels and water chemistry, there are a couple of options. The most common for beginners is to get a color test kit. Some are certainly better than others, but this an acceptable method of testing depending on which test kits are being used. The downside to these test kits is that they have a lot of room for human error because they rely on color to give results.  A more expensive option are electronic testers. While they cost more money, they are much more accurate and have less room for human error. This type of testing is widely used by hobbyist and has proven to be a successful method of testing. The last option is probe testing. It is fairly uncommon, but it is an option that allows for easy testing. Probes are generally more expensive and most beginners do not use them.

Testing Brands

There are many different brands that produce test kits. It is good to know which brands are more reliable and which are not. I will discuss a few of the better brands as recommendations.

A well known brand such as Red Sea would be expected to have good test kits. They do not disappoint with there many test kit options. They offer refractometers and color test kits for basic parameters and for more advanced parameters such as calcium, alkalinity, and magnesium. These testers can be bought in groups together or individual which ads to the convenience. Another brand that is known for having good color test kits is Salifert. Each type of test is sold separately, but they offer a very wide range of tests for beginners and much more advanced hobbyists.

The most well-known brand of electronic test kits is certainly Hanna Instruments. There are many different testers and a lot of them are for more advanced hobbyist, but a few can benefit beginners. They are more expensive than color test kits, but they are much more accurate. If you have the money these testers are definitely a better choice.

There are many different options for refractometers (salinity testers). As mentioned earlier, Red Sea has good refractometers as well Aquamaxx, but some generic refractometers can be considered as a good choice as well. There are also electronic testers for salinity, but those are more uncommon.

Finally, for temperature, most thermometers will be sufficient for a beginner. I recommend getting electronic thermometers because they are easy to read and just as cheap.

For a beginner I recommend you give all these different test options a try if you are able to and see which you prefer. I would recommend Red Sea tests for a balance of price and accuracy as well as ease of use. As a brand that mostly produces great products, I think it is safe to trust the test kits they make. Still, you may find that you like Salifert or Hanna Instruments better.

How to use test results

When you test your water you are not supposed to just shrug and move on. You need to record the results for the tests to have any worth. Also, research what parameters the water should be at. Of course different corals and fish may require different parameters, but there are general levels which parameter should be at.

Below are the standard basic parameters of a healthy reef tank:


  • Temperature: 72F-80F
  • Salinity (specific gravity): 1.023-1.025
  • Ammonia: 0 ppm
  • Nitrites: 0 ppm
  • Nitrates: 0 ppm-5 ppm
  • Phosphates: 0 ppm-0.5 ppm
  • pH: 8.0-8.4

These are just an outline of what parameters should be. If you find that a parameter is different than what it should be, then you may need to take action. Even if the parameters fall in line with this outline, your tank may still need something done to it. This is because as a reefer you should be aiming for consistency rather than specific levels. For example, a tank’s salinity may be at 1.023 the first time it is tested, but after a few days it goes up to 1.025. While it is still in range, it is not consistent. In this scenario the hobbyist would need to add fresh water.

Another thing to note is that your reef tank may do better under certain parameters than others. So it is good to record for this reason. Then you can know what levels the tank prefers and is happiest.

Water Testing is very important for multiple reasons and the different styles and techniques for testing can make it easier, harder, more accurate, and less accurate. It is crucial that you are using sufficient testing methods when testing water parameters to increase the success of your reef and health of your fish.

3 thoughts on “Aquarium Water Testing for Beginners”

  1. Just getting started in this. My new Red Sea 350 will be installed on Wednesday. This information is crucial for a correct and right path start. Thanls guys.👍🏼💪🏼

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