There is water discolouration (yellowish, brownish) and there is water cloudiness (whitish or greenish). Biologist Heiko Blessin explains the causes of cloudy aquarium water and the ways to get it crystal clear again.
You will find more on water turbidity in the Themeworld Aquarium under: Kinds of cloudiness
You can find all JBL products to combat cloudiness in your aquarium in the JBL Shop: Throubleshooter