Unexpectedly among the most frequently asked questions by our clients, the matter of cloudy water often baffles many aquarium owners. Sadly, there’s no single cause owing to numerous possible reasons. However, it’s possible to identify the cause of cloudy water based on the water’s circumstances and colour.
Grayish or whitish water
Supposing water turns cloudy shortly after filling your fish tank, it’s possibly due to poorly washed gravel. You’ll drain the aquarium and rinse the gravel thoroughly until its water runs clear.
Bacterial blossom
Usually, water doesn’t turn cloudy right after setting up your aquarium; it does weeks or months later. Often, bacterial blossom is the cause. As your aquarium goes through its first break-in cycle, it’s normal for water to turn a bit hazy. Establishing bacterial colonies to clear the waste takes a couple of weeks and at times months. With time, the cloudiness resolves itself. Excess food or decaying plants may also result in milky water.
Bacterial blooms need not cause panic. Remove uneaten food, decaying plants, debris, and routine partial water sorts out the majority of bacterial boom cases. Cut back-feeding for a day or two to curb the problem of excess food decay.

Photo credit: Freepik

Green water
A no-brainer, algae growth causes the water in your aquarium to turn green. Eliminating green water is difficult, but easier to remedy once you know the cause.

Exposure to excess light
As previously noted in our piece on maintenance tips for your aquarium, leaving the light on for long periods or placing it where it receives direct sunlight spurs algae growth.
Cut down the number of hours the tank light is on and relocate it out of direct sunlight.
Nitrates
Nitrate levels rise naturally as a by-product of waste. Water change rectifies the situation. Also, regularly clean your filter and ensure it suits your aquarium size.
Also, avoid overstocking your fish tank; otherwise, you’ll continually struggle with high nitrate levels.
The majority of cloudy water issues can be rectified by weekly 10-20% water changes, using high-quality food and clean gravel.