Soaking Requirements
When new GAC is added to the system, it is dry, and the external void space and internal pore spaces are filled with air. The GAC material only occupies 20% of the bed volume; the remainder is air. The internal GAC pores are approximately 40% of the GAC bed volume. Soaking allows the water to diffuse into the pores and displace the entrained air. Because GAC surfaces are hydrophobic, it takes a reasonably long time to wet the carbon pores and displace the air. The amount of time required is a function of temperature and carbon mesh size. Higher temperatures allow for faster diffusion; conversely, larger particles have longer pores and require more time for diffusion.