When to change media

It doesnt go bad per se, it dissolves over time and needs to be refilled.
What ph do you run your reactor at? What media are you using? I am pretty sure that it has schuran reactor media in it, so it can be ran pretty low.

 

Unless you have had a meltdown of the media, or see something else physically wrong with it I would just top it off every few months and call it good. I run schuran in my CR-4 at around 6.35 to 6.4 out of the first chamber.

 

I agree with Billy. I have never heard of replacing media unless it turns into mush. Schuran/Gen-X type media doesn't have that problem so you should be good to go. I've used the Schuran type of media before and never had any problems. It's actually what I would prefer to use. It's also cleaner than most of the media out there. It doesn't cloud up the reactor and the effluent is clean with no sandy residue.