Almost all of freshwater aquarium hobbyists experience having cloudy tank water. There have been many questions inside forums or discussion on what causes this and there are a lot of varying answers. It doesn't mean some are wrong; everything they say may be right because there are different things that may cause this. But common among the cures or solutions is water change during fish tank maintenance.
Here are some reasons that commonly cause cloudy water:
Insufficiently washed substrate or gravel - After filling your tank with water and within a couple of hours your water becomes cloudy, it may probably be caused by the substrate not being fully rinsed. What you can do is clear the tank of the water and rinse the gravel over and over until the water becomes clear. There are times that the gravel may acquire dust particles or may get dissolved thus causing the cloudiness.
Development of bacteria - There are times when the water in your tank suddenly gets cloudy despite having been clear days ago. This can be caused by development of bacteria as the water goes through the nitrogen cycle. Over time, bacterial colonies will develop in the water and in some stages, the water gets cloudy. It does not mean though that it will be bad for your fish. There are good bacteria that fishes will benefit from.
However, if cloudiness persists and you seem to be alarmed because of the way your fishes act then resort to fish tank maintenance by partially changing the water. This is after you do some testing to know the levels of pH, ammonia, nitrite, phosphates, and hardness. If your find that the results are higher than the tolerable level, then proceed with water change. Excessive plant decay, food wastes, and feces can also cause cloudy water. These may cause a rise in your water's parameters as previously mentioned and these are harmful for the fish.
Growth of algae - When this happens, your water usually turns cloudy and green. A lot of things can contribute to algal growth such as excessive lighting, too much nutrients, and a high level of nitrates. These could be solved by identifying first which caused the algal growth so you have to test the water. If it is caused by phosphates and nitrates then you need to use water conditioners that would target them and then again, fish tank maintenance by partially changing the water.
Water change will benefit your tank a lot, most especially your fishes. It keeps a controlled level of several conditions in your water thus keeping the whole system in good shape. However, crystal clear water does not also assure that everything is in tip top shape. There are times when it does not turn cloudy and yet dangerous levels of substances are present. Know more about water change and fish tank maintenance.
