Biogenic pelagic silica sediments consist of radiolarian, diatomaceous, silicoflagellate oozes, and chert. It is usually weathered limestone mixed with diatomaceous, amorphous, or crystalline silica. It can be derived from naturally occurring limestone and diatomaceous earth, a siliceous sedimentary rock. Common media include diatomaceous earth and perlite. While diatomaceous earth often performs poorly, silica gel may be effective. White paint is usually created from natural chalk, kaolinite clay or diatomaceous earth. Some filters use diatomaceous earth to help filter out contaminants. The phytoplankton consists of diatomaceous, peridinium and cyanobacteria algae. These include beer traps, diatomaceous earth, crushed eggshells, coffee grounds, and copper. Chert also occurs in diatomaceous deposits and is known as diatomaceous chert. Diatomaceous earth is widely applied for insect control in grain storage. Most of Florida's diatomaceous earths have been found in the muck of wetlands or lakes. There are some companies that use DE (Diatomaceous Earth) as pesticide. Diatomaceous earth is sometimes found on desert surfaces. One form of diatomaceous earth is used as a filter medium, especially for swimming pools.