I occasionally run carbon after something tries to wage war or overgrow another specimen. I used to run carbon 24/7 but got lazy and decided it wasn't necessary. I buy carbon that is not ground into little pieces. It's easier to deal with when bagging and installing and doesn't seem to have the amount of dust when you rinse it. Larger pieces allow water to flow through it easier, too, because of the amount of space between particles. It does not need to be Kent brand. If your water tends to yellow, you will likely notice a clarity improvement by running carbon.
Also, remember that once it is saturated (full) it needs to be removed/replaced.