Ok so random question, laying awake late at night thinking about fish, as you do! it occurred to me that given bacteria in tank/sump will only multiply to a level that the waste in tank can sustain/feed, why do we load up our sumps with so much expensive bio media? Surely the amount of bacteria required for a given number of fish would be housed in far less or even on cheaper foam pads. Some will claim low flow areas at centre of bio media, but surely the 2 inches of sand over floor of aquarium has masses of low flow anaerobic capacity? Just a thought and would love to hear peoples take on this. 🫣