aquarium test kit

How To TEST Your Aquarium Water

In Aquariumsby PaulK


Testing your aquarium water is one of the most important things you can do. the problem is knowing what to test for and what levels of toxins are acceptable. If you’re struggling with testing your aquarium water, I’ve created a guide below to help you out.

The three main things you need to test for are ammonia, nitrite, and pH levels. I’ll add a fourth, which is chlorine since most city water contains it. Ammonia and nitrite levels should be zero or very close to zero no more than two to four parts per million. You may see nitrate levels but that is okay for the fish, and if you have live plants, they should absorb it. pH levels depend on the type of fish you have. A 7 pH is considered neutral. Lower than that is acidic and higher than that is alkaline. Normally, freshwater fish survive in water in between pH 5.5 – pH 7.5. Sudden changes in pH can be fatal to your fish, so it’s important to monitor.

How to test fish tank water for ammonia

API FRESHWATER MASTER TEST KIT 800-Test Freshwater Aquarium Water Master Test Kit If you’re using a test kit like the API ammonia test kit or master test kit, then you want to grab the two solutions that are used for the test. First, rinse the test tube with the water that you are going to test using the dropper. Empty the test tube and add the test water from the tank you want to test up to the five ml mark. Put eight drops from each bottle into the test tube with the water. Shake for five seconds and let sit for five minutes. You should have a chart with colors that you want to compare the color of the water to in order to get a reading on ppm. Basically, you want a zero ppm reading or a yellow color before adding fish.

How to test fish tank water for nitrites

This test is similar to testing for ammonia. Grab the nitrite test solution. There should only be one bottle. Make sure you read the label to get nitrite and not nitrate. Again rinse the test tube with test water and then add the water from the test aquarium up to the five ml line and add five drops of the nitrite test solution with an eyedropper. Put the cap on the test tube and shake for five seconds, then let sit for five minutes. After five minutes check the color of the solution and compare it to the chart provided. Double check that you have the correct chart. It should be blue in color for zero nitrites.

How to test pH level

The main thing with pH is to not chase the pH number. In other words, don’t try and manipulate the water to get to a certain pH level. It’s better to acclimate the fish to the pH level of General Hydroponics pH Control Kit your water, whether it be tap or well water. The fish you get are most likely from the pet store and not wild. So the fish are born and bred in the fish store environment and with the pH level that is in their water. So first find out your water source pH level, then get the fish that will survive in that pH level.

For pH tests, you can do the water test kit or a digital measurer. I’ve tested both and they come out pretty close, so either one works. The digital tool is easier to use, so it may be worth it to invest in one. They’re fairly cheap.

What pH level is good for tropical fish?

Remember that pH is an exponential scale, not linear, so every pH level on the scale is times 10. You don’t want to go too far from 7 neutral either way. Stay between 6 and 8 depending on the type of fish you have.

Saltwater fish need a higher pH more alkaline environment, so anything around 8 pH is fine. Most likely, you have freshwater fish, so between 6 and 7.5 is an appropriate range.

Here are preferred pH levels for some common freshwater fish:

Goldfish: 7.0 – 7.5
Angelfish: 6.5 – 7.0
Neon Tetra: 5.8 – 6.2
Tiger Barb: 6.0 – 6.5
Zebra Danio: 6.5 – 7.0
Guppies: 6.8 – 7.8

Are aquarium test strips accurate?

It’s tempting to use aquarium test strips because they are easy to use. The problem is they are not very precise. If you compare the strip pads to the color scale on the box, you’ll see quite a jump in parts per million between the colors. It’s hard to get very precise with such a jump. Also, the 5 in 1 kit force you to test for all five parameters at a time and don’t come with a test for ammonia, the most important test! You’ll have to purchase that one separately.

If you do use strips, be aware that there is an expiration date on them. Don’t use them beyond expiration.

When you compare the costs of a water test kit vs. test strips, the water test kit definitely has more value and is more accurate.

Electronic aquarium water tester

The latest thing to come out now is an electronic aquarium monitor like the Seneye. It has to link to your PC and then to your smartphone. I have not used one myself, so I can’t really recommend or not recommend. They’re rather pricey at around $150 and have mixed reviews on Amazon. I think advancements will be made in this area, so I would hold off for now. Love the concept, but the jury is still out.

How to lower ammonia levels in your fish tank

There could be a number of reasons that you are experiencing ammonia spikes. If you have a new tank, it may not have built up enough good bacteria in the media to absorb the ammonia. In which case, you should let the tank cycle longer.

It could be you’re feeding your fish too many times a day and there is food waste in the substrate producing ammonia. Cut back on feedings if this is the case.

It could be other organic material such as dead plants or even dead fish that you don’t see (notice any missing?). Vacuum and clean the substrate to eliminate waste.

You should try and find the source, so you can take care of the problem.

The most effective way to reduce ammonia is to do a 50% water change which will dilute the ammonia.

You may have introduced too many fish in a new tank. When you’re starting out, you only want a few fish. As you go along establishing the tank, then you can begin to slowly add more fish.

How Can You Tell If There Is Too Much Ammonia?

If you don’t have a test kit, you need to watch your fish very closely.
Here are some signs that there is toxic ammonia present:

  • Your fish are not eating their food. Lack of appetite.
  • You’ll notice slime coat or some discoloration on their scales.
  • They’re gasping at the surface for oxygen (should be pretty obvious).
  • Erratic swimming or darting. Trying to jump out of the water.
  • Hiding, bottom sitting.

These are all signs that your fish are struggling. You need to act fast and do an immediate water change to remove the toxins.

Testing for Chlorine

If you’re like most people, you probably have city water that contains chlorine and chloramine. This was brought about by the Safe Drinking Water Act of 1974 in the US. I’m not sure about foreign countries. That’s why it’s a good idea to test your water source to see what’s in your water. For most cases, you want to run a simple chlorine and chloramine test and then treat the water if it’s present. Chlorine and chloramines are good for eliminating contaminants for human drinking, but not so good for fish.

Here is a kit that tests for chlorine. It’s actually for pools but works just fine for tap water as well. You can get more extensive kits that you send off to a lab and get the results back in 10 days or so. Quite a bit more expensive, but they test for over 100 chemicals including lead, arsenic, heavy metals, e-coli etc. It may be worth it for you and your fish.

So what is chloramine?

Basically, it’s a chemical compound that contains molecules of ammonia and chlorine. It used to be that you could allow the water to sit for days in the open air and that would eliminate the chlorine, but you can’t really get away with that anymore because of the chloramine. This is why you need a water treatment that gets rid of both chlorine and chloramine.

How to test for Nitrates

Not to be confused with nitrites, which lower the amount of oxygen in a fish’s blood and can be lethal. Nitrates are a less harmful byproduct from the beneficial bacteria in the filter system.

Even though Nitrates are less harmful, they should be monitored as part of the test. Generally, you want below 50 ppm for test results. If you have live plants in your tank, the plants will absorb some of that nitrate as well as other chemicals in the water. That’s part of the reason live plants are recommended for freshwater aquariums. Nitrates will also contribute to algae growth, so it’s a good idea to have healthy plants.

Other ways to reduce Nitrates:

  • Keep your tank clean including substrate
  • Don’t overfeed your fish
  • Do regular water changes

Testing for Nitrates

If you are using the API Master Water Test Kit you’ll have two bottles of testing solutions. Fill up the test vile with your aquarium water up to the line. You will have a convex shape that the water forms in the tube. The bottom of the convex shape should be even with the line. First, you put ten drops of the first test solution in the test water and shake vigorously. Then for using the second bottle, you must shake it vigorously for 30 seconds before adding ten drops to the test water. After you shake and add the ten drops, let the solution sit for about 3 minutes and then compare the color to the chart provided. If the ppm is showing above 50, then it’s time for a water change.

Testing For Phosphate

Phosphate is another element you should test for in your tank. Phosphate is not harmful to fish but causes significant algae growth in freshwater tanks. Most test kits don’t include a phosphate test and if they do are really hard to read. It’s better to get an electronic phosphate tester like this Hanna phosphate checker.

Phosphate generally comes about from the food you feed your fish. That’s why you want to watch how much you feed your fish. If you use frozen food, you’ll want to thaw and thoroughly rinse the food first. A lot of pellet and flake foods contain polyphosphates so you may want to read the ingredient list first. It may be that your home water supply is high in phosphates, so you want to test that as well. You may look into installing a reverse osmosis system for your home. Over the years they have become affordable.

Ways to control Phosphate:

Change or clean your mechanical filtration often to clear out debris that could break down.

Use a product such as GFO that binds the phosphate to your mechanical filter

How Often Should You Test?

This will depend on a number of factors. Is your fish tank in the process of cycling or is it already cycled? Is it lightly or heavily stocked with fish? Do you notice something wrong with fish behavior or is there an increase in algae growth? Etc. etc.

If you’re just starting to cycle your tank, then you want to test every other day until you are comfortable that the water parameters are acceptable. Like 0 ammonia, 0 nitrites, and under 50 ppm of nitrates.

If your tank is already established and cycled, then probably once a week before water changes unless you notice problems.

Basically, testing the water should be built into your regular routines like cleaning the tank, cleaning the filters, changing the water etc. An ounce of prevention goes a long way towards a healthy fish tank. is a participant in the Amazon Affiliate Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to

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