Do I really need carbon in my filter?

After years of not using I added Carbon to my system last month. My question is how often should I change it and how much should I use. I have it in a pouch in a empty canister filter that I use to supply my chiller.

 

It needs to be changed every 2 weeks since bacteria starts to grow on it, and the stuff it pulls out of the water ends up in the pores, so it can't absorb any more. Sometimes it only takes 1 week for that to happen, sometimes 4 weeks, but 2 weeks is a good happy medium, and fairly average.

How much you should use is super dependant on your tank. How many gallons, what chemical-making inhabitants (fish, algaes, chalice/zoas/paly/other corals) do you have?

 

I guess it is time for me to change it than. It has been in there for 4 weeks. I have a
90g. with 30g. refugium. 2 250 mh / 4 t5 accent.
90 lb. lr 80lb. Fiji pink live sand.
2 Clowns, 2 Yellow tail Damsels, Flame Angel, Fox face, Yellow Tang.
2 Cleaner Shrimp, Fire Shrimp, Snails, Hermit Crabs, Sea Cucumbers, 2 Feather Dusters.
This is being upgraded to a 150g as time allowes. The sooner the better.

 

Yeah, you definitely want to change it every 2 weeks. Algaes make quite a bit of those yellowing products, so your carbon will clog up on the quicker side.

 

How much do you think? I used about 2 cups.