I have it all, coarse, med and fine. if it is for a sump I 100% recommend using 4" thick pieces, 2" is too flimsy.
coarse really doesn't need to be cleaned but doesn't capture much junk, great for bio filtration and some mech filtration.
--shrimp will love coarse they burrow through mine and disappear inside it eating what they eat.
med captures a lot of junk and had even more surface area for bb
fine really gets filled up with slime, I didn't clean a 2" thick piece for months and then when I decided to it took me at least half an hour under hot tap water while wringing and squeezing it before it ran clean. but there was never any problem with flow through it.
now I just run the coarse and the fine. the medium is cut up to use in an AC 70.
I will probablu ditch the 2" fine and maybe add another 4" coarse and 4" fine.
or I may leave it as There are no problems in my tank as far as parameters....
20L My Other Tank: OEBT Shrimp
40B Inlaws Tank: 2 goldfish
75 Main Tank w/ sump: 5 Glossolepis pseudoincisus, 5 Melanotaenia boesemani, 10 Melanotaenia praecox, 5 Melanotaenia lacustris, some cories, a bn pleco and rainbow fish fry