Hi, a water tank will be put in the third level floor or slab. What must be the volume if gravity tank will be used so the pressure would be strong at 2nd floor and ground? It will be primarily a wet fire system. The tank won't be used for any other water applications since the building already has water line. Any website to compute for it as well as pipe size to ensure strong pressure? Also are gravity or pressurized water tank recommended for such kind of usage? Thank you.