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How to Test Fish Tank Water Without a Kit

How to Test Fish Tank Water Without a Kit
The purpose of this blog is to share general information and is written to the author's best knowledge. It is not intended to be used in place of veterinary advice. For health concerns, please seek proper veterinary care. In addition, as an Amazon Associate I earn from qualifying purchases.

Have you ever wondered how to test fish tank water without a kit? I sure have!

Testing your tank’s water with a test kit is easy and straightforward. But unfortunately, kits are often expensive and, in some cases, difficult to find.

For this reason, I’ve made a guide on how to check the quality of your tank’s water without using a test kit. Let’s get started!

How Can I Test My Aquarium Water Without a Test Kit?

Unless you’re a biologist or ichthyologist, it’s almost impossible to test your fish tank’s water without a test kit. After all, you can never truly know the quality of your water without the appropriate resources.

If you don’t have a test kit to hand or are simply unsure of how to test the water yourself, bring a water sample and have it tested at your local pet store or Walmart.

Some stores do it for free, while others charge a flat fee for monthly testing. Compare their monthly cost to the actual cost of a test kit and decide if the monthly fee is worth it.

With that said, a good all-around test kit usually costs anywhere between $20 to $50. It tests all the important aspects of a fish tank, including pH, ammonia, nitrate, and nitrite.

If you’re planning to own or already own fish, it’s always worth spending a few dollars for a good water tester.

Are There Ways to Tell If My Fish Tank Water Is Healthy?

Although you can’t test a fish tank without a kit, there are several ways to tell if your fish tank water is healthy or not. These are as follows:

Behavioral Changes in Fish

Betta Fish at Top of the Tank

If you’re a dedicated aquarium hobbyist, you’ve probably spent hours just watching your fish swim around your tank.

Although you can’t really play with your fish, it’s relatively easy to tell if your fish is healthy and happy by observing their behavior.

Knowing the difference between “normal” and “abnormal” fish behavior is the key to understanding the state of your fish and the long-term success of your aquarium.

Unexpected behavioral changes in fish are often a sign of poor living conditions and/or the presence of increased chemical compounds in the tank (ammonia, nitrate, nitrite, etc).

If not immediately taken care of, the conditions of your fish’s water can cause stress and even sickness.

The symptoms below are all possible signs of improper water conditions:

  • Decreased appetite
  • Fish gasping at the surface
  • Red gills
  • Hiding or darting around the tank
  • Resting at the bottom of the tank for prolonged periods
  • Yawning
  • Listless or erratic movement
  • Difficulty swimming
  • Heavy breathing

If your fish still exhibits the above symptoms even after changing the water of your tank, it’s worth consulting a professional to rule out any disease. The veterinarian may require a 100mL sample of your aquarium’s water so make sure to bring one just in case.

Cloudy Water

Cloudy water occurs for a number of reasons, including gravel residue, bacterial blossom, dissolved constituents (i.e., silicates, phosphates, or heavy metals), and algae growth.

Usually, cloudy water isn’t harmful to fish and will clear on its own. Let nature take its course for 2 to 3 days and see if any changes occur.

If your water doesn’t clear after 5 to 10 days, it’s safe to assume that there might be a problem with the tank’s water quality.

Tanks with high levels of dissolved constituents will likely test for high pH (alkaline). Treating the water with conditioners usually solves this problem.

You can also connect an RO (Reverse Osmosis) water filter to your water tank to filter out and reduce solid substances, foreign contaminants, and harmful minerals from the tank’s water.

Green Water

Fish in Green Water

Green water is often caused by excess algae growth in your water tank.

Algae don’t usually cause much harm to your fish and other aquarium critters. In fact, some phytoplankton species (Tetraselmis, Thalassiosira, Nannochloropsis, and Isochrysis) are quite beneficial.

This is because they remove phosphates and nitrates, oxygenate the water, and even consume carbon dioxide to stabilize the water’s pH.

Some aquarium owners actually add phytoplankton to their tanks so their fish can live longer and healthier.

With that said, some nutrients, particularly nitrates and phosphates, support the growth of algae and must be reduced to prevent the decline of water quality.

To keep the levels down, you need to get rid of their source. Nitrates naturally occur from the byproduct of fish wastes, while phosphates develop from decaying matter (e.g., fish food and dead/dying plants) and the water source itself.

The only way to determine the nitrate and phosphate levels of your tank is to test your aquarium water with a test kit. This will help you figure out how serious the build-up is and how much action you need to take.

If the nitrate level is over 40mg/l (40ppm), or even close to that number, take action immediately. Likewise, phosphate level shouldn’t exceed 0.05mg/l (0.05ppm).

To reduce and prevent nitrate and phosphate build-up, consider the following:

  • Don’t overfeed your fish
  • Avoid overstocking your tank
  • Invest in de-nitrate filter media
  • Add nitrate-feeding live plants and live rocks in your tank

If the above options don’t seem to work, consider water treatments and chemical additives that are specifically formulated to reduce high levels of nitrate and phosphate. Make sure to consult your local pet store or veterinarian before using any additive or treatment.

Ideally, they should only be used as a final course of action and never for long-term instances.

What Should I Test?

A good all-round tester kit should measure the following:

  • Ammonia – Must be no greater than 0.0ppm or undetectable
  • Nitrite – Must be no greater than 0.0ppm or undetectable
  • Nitrate – Must register below 40ppm
  • pH – pH must range from 6.5 to 7.5 for freshwater fish and upwards of 8 for saltwater fish
  • Phosphate – Must be no greater than 0.05ppm

Final Thoughts

Unfortunately, it’s almost impossible to test fish tank water without a kit.

If you don’t have a kit available, you can take a 100mL water sample to your local pet store or Walmart and see what they charge for water tests. Some do it for free, while others do it for a minimal cost.

To guarantee the health of your water tank, change 25 to 50% of your water every two to four weeks. Also, make sure to stir the gravel during the water change.

Keep reading: Simple Tips to Clean Fish Tank Gravel Without a Vacuum.