I'm starting to run Carbon in my phosban reactor. I used to run it on my larger tank and would run it 24/7 and change it every 2 weeks. I used ROX and pushed it with a Maxi-jet 1200. So, I've been doing some reading and most says that the Carbon is depleted after about 2-4 days, others say to run it and change it every 2 weeks, which I was doing previously. So, is it a waste to run it 24/7? What should the monthly routine be for carbon? By the way this is for 70 total gallons of water. Thanks.