Carbon, with a planted tank?

^My method to estimate the working time is based upon an extremely scientific empirical approach.

First I lift up the tank hood.

Second I tank a sniff.

If tank smells like a pond it's time to switch out the carbon.

I use carbon to remove the volatiles and aromatics from the tank. I started this when my wife was pregnant with my son. Pregnancy amplifies the sense of smell in many women. Any guy having to haul out the garbage 4 times a day for 9 months can verify this.

I've kept it up since then because I've never found another filter media that can keep a 125 gallon goldfish tank crystal clear. It's is a little expensive running me about $15 a month for a tank that size but worth it for being odor free.
 
To use carbon,or not to use carbon is a really up to you.In a 20 gallon planted tank,I wouldn't waste your money on it.I only use it in my larger tanks,or in tanks with messy fish.I am just in the habit of using it in these tanks,they would probably be fine without it.I change 50% of the water in all of my tanks every week.Water changes,not overstocking,and not overfeeding,are the key to a clean tank,IMO.
 
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