mines is expose to the light. i put a net over it so little bugs such as ants can't get in. I will cover it as soon as i get the water pump and nozzle. all these time i thought dirt was sucked in by the air pump and flowed through to the air stone, then to the water. I'm doing a manual feed. I just think that using the water pump attach to nozzle will be much easyer to feed in scrog instead of pouring cup after cup.