Quote Originally Posted by Rockafeller85
how do you know when to change the filter?
is there a formula or general rule?
Most of them, will say 6-12 months... I know they can last longer or less. Depends how often its on and how much activated carbon comes accross smells that require (are automatically) caught by the filter!!

But my general rule is, if it smells dank, swap your coal tank..

:thumbsup:

checkout my grow log too, just installed my own cooltube..

Peace,
Denial