Fluidization of media is a very simple and effective method to increase the surface area of a given substrate to increase the transfer rate between the liquid and solid phases. Typically the substrate is fluidized using a controlled velocity of fluid to convert the substrate from a solid state to a liquid like state. Fluidized beds have many advantages including high transfer rates when used for chemical filtration as well as huge surface areas when in use as a biological filter.

Fluidized reactors used for chemical filtration in reef tanks typically contain phosphate adsorbing media, either granular ferric oxide (GFO) or alumina oxide (AO). GFO is typically used however due to some risk of releasing aluminum back into the aquarium water when using AO based media. GFO based adsorbents such as Rowaphos or Phosban are very popular as they will remove both organic and inorganic phosphate from the aquaria at a very rapid rate. Some care must be taken to reduce phosphate levels at a slow controlled rate or rapid tissue necrosis (RTN) can occur. However if low phosphate levels are achieved in a reef aquarium it will help reduce nuisance algae, increase coral health, color, growth and improve the reef bioload. It is a goal in maintaining a reef tank to keep nutrient levels such as phosphates at or close to zero (0-undetectable).

Granular activated carbon (GAC) is widely used in fluidized reactors as well as Purigen which is a synthetic adsorbent which has similar affinities toward organics comparable to GAC. Purigen will not adsorb trace elements or other metals such as carbon does which may be a benefit when the goal is to reduce Nitrates in a reef tank.

Overall fluidized reactors can play an important role in the reef aquarium. Not necessarily by providing biological filtration but as a means to export unwanted chemical elements from the captive reef by the use of the different types of media available to the reef keeper