Marineland Activated Carbon (10 oz)

This 10 oz container of Marineland activated carbon is among the best quality on the market, yet sells for a lower price than most of the "designer" carbon brands that are actually not better, or not much better, yet sell for more, sometimes much more. You have to be careful also because there are also other brands of low-cost carbon that are inferior in quality.
 
We recommend changing the carbon every two-weeks for high density or sensitive organisms and every four weeks (or once per month) for medium to low densities or average organisms. We do not recommend allowing the carbon to go more than a month, especially not more than two months (if you get behind on maintenance) due to buildup of organic matter in the carbon, that will eventually become toxic and risk for disease & parasites.
 
The carbon will cause the water to become crystal clear clean. If discoloration of the water occurs this is also an indicator that it is time to change the carbon.