The Pax Bellum ARID C30 Macroalgae Based Bio Filter utilizes macroalgae (specifically Chaetomorpha) to function as a tunable nutrient export mechanism. The unique design of the ARID incorporates a coaxial LED light tube to maximize light penetration and efficiency.
The tube and flange design of the device serves to isolate the algae from atmospheric CO2, which effectively limits the carbon source for the algae to only that which is respired by organisms within the aquarium. This is a self-regulating feature and eliminates organic carbon buildup (yellowing of the water).
The ARID is analogous to a lung for the aquarium, by supersaturating the aquarium with oxygen created by the algae during its respiration while removing excess CO2.
Pax Bellum recommends running the ARID on a "reverse daylight" cycle (i.e.; opposite of the display aquarium) which helps to balance the natural day/night pH swing that occur, and to maintain high dissolved oxygen levels throughout the night when the display aquarium lighting is off and photosynthesis has ceased.