I had a fowlr & ran carbon 24/7, then went reef. I did some research & found that carbon can remove good things as well as bad, however lots of people with reefs run it 24/7 & swear by it!!! I run carbon about once a month for a day or so depending on several things ie. if I medicate, cloudy water, or just to clean it of bad stuff that may end up in the water from the local surroundings , like in my house hair spray
. Its somthing that I think each reefer has to find out on there own what to do, thats why I still run it from time to time but not 24/7 anymore, its my own prefrence & its working fine......I also run a big uv its timed.