anyhwo im calculating what size pump i need for my new filter. heres how to calculate flow requirments for a fluidised bed filter. keep in mind you can have a fluidised bed filter as high as you want but the diamtere is what dictates pump size and vice versa. ok so you basically want to figure out how many cm ofthe cylinder gets filled every second. so lets assume you have my situation.
pump that pumps 11,400 lph and a cyclinder diamter of 200mm. well lets calculate the surface area of cyliner (pie r squared) 314cm
lets get a litres for say 15cm height 4.71 Litres. my pump does 3.1 litres a second
divide 4.71 by 3.1 you get 1.519. then divide 15 by 1.519= 9.8cm of the cycliner filled per second. so will the sand fall that far in a seond ? nope so we know our pump is strong enouht to suspendt he sand.