Hydrocarbonate Reactor 400 by Aqua Medic. **** PRODUCT MANUAL **** The Hydrocarbonate Reactor 400 is also a Bypass Reactor but it is filled with hydrocarbonate media and is meant for use as an exit stage for the effluent from your Sulphur Reactor. This is essential as the Hydrocarbonate media re-buffers the pH that was dropped by the sulphuric acid introduced by the biochemical reactions within the Sulphur Reactor. Though the Hydrocarbonate Reactor 400 may be useful in other aquarium applications it should be considered an essential partner component to your Sulphur Reactor. Can also be used as a secondary chamber for calcium reactors. * Diameter 80 mm (c. 3.1") * Length 35.5 cm (c. 14") * Hose connection 4/6 mm (c. 1/4")