You are facing a problem if your yellow water is due to dissolved organic carbons. This is a waste issue. You have a DOC problem if your water is cloudy, you have no aquarium wood in your tank, fish are sick or dying and there is an unpleasant odor. You may see clumps of decaying waste or dead plants. This problem is more common in brand new tanks and tanks in which you've recently switched to a new type of food. Improper filtration, infrequent water changes, dying plants, dead fish or invertebrates in the tank, overcrowding, leftover fish food and uncured gravel all contribute to DOC. Dissolved organic compounds can cause "toxic blooms," whereby microorganisms growing in the DOC deplete the oxygen in your tank and cause fish death.
What cause cloudy white aquarium water? | Algone
Continuing Paul and Jen’s saga; they emptied the tank and completely rinsed the gravel. The tank was refilled with water treated to remove chlorine and chloramines, a few easy to grow aquatic plants were added and they began the ‘fishless’ method for cycling their tank. All seemed fine for a couple of days until the aquarium water suddenly turned green. It looked like pea soup. The green color was the result of a massive algae bloom instigated by the tank being blasted from direct sunlight from the large picture window. Rather than move the tank, they conducted a partial water change and chose to block the direct sunlight by installing decorative aquarium background material outside of the tank along the back and sides. Additionally, the window’s shades were closed to prevent most of the sunlight from striking the tank. Surprisingly, green water reappeared. Consulting with an experienced aquarist, Paul and Jen learned they were perpetuating the problem by leaving the aquarium light running 24/7 and should connect the light to a simple on/off timer. They also learned that green water can result from excess nutrients building up from overfeeding and from a lack of regular tank maintenance such as partial water changes.
Poorly rinsed gravel in a new aquarium can cause white cloudiness
Normally, they did gravel cleaning and a partial water change a few days apart from filter cleaning. What they experienced is called a bacteria bloom which is a sudden increase of bacteria in suspension. The bacteria reproduced so quickly that they actually became visible like fog. It is the prevailing cause of cloudy water. Bacteria blooms are usually seen in tanks that are not completely cycled or in an established aquarium that suddenly experiences a massive cleaning. Other causes of bacterial blooms are from large quantities of dissolved organic compounds (DOC) which include uneaten food, decaying plants or dead fish.
How to clear cloudy aquarium water | Algone