I had 2 canisters with ceramic and floss, chemi pure in the small 12 gal cube. Problem is with kids you have no idea how many times he managed to convince "mommy" the fish are hungry
no matter what you tell mommy.
Power went out one night for 6 hours and all fish & inverts perished. No more canisters for me. Upgraded to a 29gal, next step is skimmer next to media basket and later on as a winter project I'll build a sump - anywhere from 75-100gal, yes you read right, budget depending- so that the water column is stable and I am able to add more rock, inverts, cheato ...large skimmer and all the other goodies that limit the cube.
Why not go bigger you say ...it's my son's tank. I'd probably have my bones broken if I took it apart.