I leave the back panel to get as green and fluffy as it likes. Turna out bash cant stand to see his own reflection so I leave the back to go naturally green to help his attitude a bit
It also adds oxygen to the water and helps keep nitrate down. Looks more natural also. You might catch him having a munch on some of it from time to time.
Beats having it in a bare acrylic box with no oxygen or enrichment and then wondering whats wrong with it.