Clear, simple solutions for clean, sparkling water.


Good water quality is essential for successful fish keeping. It is estimated that 90% of fish diseases resulting in death are caused by poor water quality and lack of maintenance. Poor water quality suppresses fish immune systems, allowing disease to take hold. Therefore, it is vital to ensure fish are well looked after and proper water quality is maintained.

In an aquarium, we need to manage water quality through filtration, water changes and other preventative maintenance like the use of water treatments and carefully managed feeding. There’s a lot that can affect the water quality in your aquarium. If you’re experiencing an issue, don’t worry: It happens to even the most seasoned fish owners. Below are three of the most common problems and how you can easily correct them.

1. The water is cloudy

Cloudiness is usually caused by one of three things:

  • Overfeeding: Uneaten food decomposes, which can cloud your water. Feed your fish two to three times a day but no more than what your fish can eat in one to two minutes.
  • Overstocking: When you have too many fish in your tank, excess waste gives off ammonia and nitrites, which can also cloud your water.
  • New tank syndrome: An inexperienced fish owner may not realise they have to prepare their new aquarium’s filter to handle fish waste through a process called ‘cycling.’ An ineffective filtering system and lack of good bacteria in your tank creates elevated levels of ammonia, which can harm the fish and result in cloudy water. So when you first set up your aquarium, be sure to condition and cycle the water right away. Give it time to get the conditions right, before you add fish.

How you can get rid of cloudy water

  • Be sure your filter is properly rated for the size of your aquarium.
  • Monitor and change your filter cartridge on a regular basis – ideally, at least once a month. Twice a month if you have a lot of fish, or if you have fish that produce more waste, such as Goldfish or Cichlids.
  • Clean your filter of any sludge, particularly if it has an impeller, every other month.
  • Do a 25% water change once a month.
  • Reduce the amount of food you feed your fish.
  • Have a Petbarn team member test your water, or purchase testing strips. High ammonia and nitrites would indicate excess food or waste. A 25% water change will bring down these levels until you can fix the problem.

2. The tank water is green

If your aquarium’s water has turned green, you have excess algae. This can be caused by:

  • Having too much direct sunlight on your tank.
  • Overfeeding.
  • Having a high level of phosphates in your water supply.

Solve your green water problem quickly and easily

Do a 50% water change. Then, scrub down the insides of the glass with a magnet scrubber or scraper (but please, no soap!).

  • Remove any artificial plants and ornaments, and clean them with a distilled white vinegar solution, a 1:1 ratio or less.
  • Cut back on your feeding: only once or twice a day in small doses.
  • If your water source is high in phosphates (which you can find out by using a testing kit, find a new water supply like bottled water, or perform smaller, more frequent water changes.
  • Dose with an algae control substance.

3. Your water smells terrible

A bad smell is usually a sign of excess waste, and is most often linked to excess food. Here are a few steps you can take to breathe easier:

  • Test your water for high ammonia and nitrite levels. Then, to correct this problem, change out 50% of the water, wait a day, and then change out 25% more.
  • Cut back on your feeding.
  • Make sure you have the proper sized filter for the size of your aquarium.
  • Don’t overstock your tank.

How warm should my tank be?

The temperature of your water is also an important consideration. To make temperature reading easy, consider purchasing an adhesive temperature strip that can be applied to the outside of your aquarium glass. They’re inexpensive and available online or in store at Petbarn. When it comes to heating:

  • Never place an aquarium above or near a heat source or air conditioner.
  • Submersible heaters are the most popular. Some are adjustable. Others are pre-set for your convenience.
  • Be sure to purchase a heater that’s properly rated wattage-wise for your tank.
  • Never remove a heater from the water if it’s still turned on. Unplug it first, let it cool to the touch and then remove it.

Why do I need to test my water?

In nature, waste products from decaying matter (fish waste and other animal waste) are naturally filtered. Bacteria and plant life remove the harmful ammonia and nitrites. The substrate (gravel) at the bottom of a body of water will absorb harmful chemicals and decaying matter like a natural filter.

In an aquarium, the natural filtration is replaced by equipment, which filters the water. The larger the aquarium you own, the easier it is to keep the water balanced and healthy. To ensure the ammonia and nitrite levels have not reached harmful levels, it’s important to test the water.

Feel free to chat to a Petbarn team member if you have any more questions about your aquarium’s water quality.