wetside direction

[NyReefNoob]

never really payed attention, but does it matter what side faces up ? the more open vented side or the solid side ?

[Ph0ton]

I usually put the solid side down. It seems to keep my sand from blowing around as much.

[EcoTech Marine]

The solid side can be used to block a vortex if placed up or prevent sand from being blown around if placed down. It's up to you.