Do carbon filters work or waste of $$$$?

[ijeh99]

I was informed to keep my bag of charcoal in the filter all the time for up to 6 months and then replace it.

 

[jlem]

I agree that carbon probably is pretty useless chemical wise after a few weeks at the very most. Keep in mind though that 16oz will absorb alot longer than 4oz will in the same tank. I like the monthly thing. But as you can see this is just my personnell preferance

 

[ijeh99]

The charcoal I have in my filter currently is Chemi-pure - would six months be too long to replace it with another one considering I have a 25 g tank? How does one know when to replace it or do I just pay attention how many weeks have gone by?
Should I stay away (like suggested by a LFS) Hagen's Ultr-Ex Filter Carbon (I have a brand new box purchased many months ago before I started SW) or may I use it up when the time is needed to replace my charcoal.

 

[ijeh99]

The Chemi-pure charcoal is 10 oz.