Normally filter canisters are all roughly the same, 3 or 4 trays for different medias.
Water goes in from tank intake pipe directly to bottom of filter then water goes up from bottom of filter media compartments going through each tray of media until through filter and back to the tank through spray bar or nozzle at opposite end to the intake pipe.
But some folks set this up differently depending on their tank set ups but as a general rule that’s how it goes.
In most cases it’s the coarse sponge media that’s first for water to go through at the bottom tray, then ceramic/matrix media in middle tray and then bio media with filter floss on top of the bio media.
That’s the way I generally had my canister filters set up.
It does not really matter which order the bio media and the ceramic media trays goes in to be honest imho the coarse sponge media is always first and the final stage being the filter floss at very top to collect the last of the tiny particles of gunk/debris to keep the water real clean before it goes into the tank.
The filter floss is best changed at every filter maintenance clean, you can get a roll of filter floss and cut it out to size and shape of the filter, much cheaper way of doing this as manufacturers or LFS tend to grossly overcharge for just a few pieces of this filter media!
(Btw do rinse filter floss out first before adding to the filter, this gets rid of tiny bits of floss and dust)
