From The Aquarium Wiki
Detritus (Day-Try-Us hear)(also known as Mulm) is the decaying organic matter from decomposing dead plants or animals lying on the substrate in your tank. This material is a very important source of nutrients for tiny creatures like infusoria which some fry species require to eat at first.
Usually detritus will accumulate in low water flow areas, sumps, edges of rocks, ornaments, etc.
Bacteria and fungi will eventually break down detritus into its chemical components and plants will feed upon this rich source. So planted aquarums rarely remove detritus.
If you do not have a planted tank then detritus can look unsightly and unwelcome. It is a source for potentially harmful bacteria and fungus to live and breed.
- You can use a vacuum system to suck up this material and throw it away.
- There are several bottles on the market which have vast quantities of bacteria in them which will rapidly consume detritus before they too die harmless into the water. Examples are Waste control by Nutrafin or Sludge Buster No. 15 by Interpet.
- Adding bogwood to your tank will encourage organisms which break down detritus.
- Adding Potassium permanganate will break up detritus dissolved in the water.
- See also Mulm.
- Detritus by Wikipedia