So What's Wrong with Carbon?

Here is a site I visit and an old write-up about the use of AC. As with any tank of course, the variables of bio-load and other filtration being utilized. If you google AC and marine filtration, you will find articles that reference longer life times than 3-4wks, based upon water flow, quality/quantity of AC, and other factors.

Sirdarksol - this article also mentions a method for measuring AC performance in a tank.

www.malawicichlidhomepage.com/aquainfo/activated_carbon.html