Fit a pressure release bypass if using pumps with delivery heads exceeding 10m* (33 ft.). The filter pressure rating is 1.5 bar (*0.7 bar/ 7m head for BBF-XS). Very heavily stocked ponds require more frequent turnover than the 2 hours suggested above. Multiply Imperial gallons by 1.2 for US Gallons. Dimensions and backwash volumes are approximate. We undertake continuous product development and specifications may change.