when is carbon exhausted?

[kenny]

When is carbon exhausted? Is there a test?

 

[bang guy]

Everything I've seen indicates it is exausted in about 24 hours. I'll admit this is a controversial point of view on my part but I've not seen a scientific study that disputes my point of view concerning GAC and Saltwater.

 

[califishdude]

i have read that they are useless after a few days and will cuse your levels to go up if kept in your filter. i had a suggestion from the board to remove my from my fluval and get a filter floss, and bio-chem. the bottle of bio-chem to change it every 3-6 mos, it has something in the besides carbon

 

[tygerfifteen]

does that apply to carbon for like an aquaclear 300?

 

[jlem]

The three books that I have all say that carbon should last several weeks at the minimum. Granted if you put a teaspoon full in a fully stocked 125 gallon tank that is in bad shape it won't last anywhere near that long, but 32 ounces in a normal stocked 55 will probably last at least a month. I can only speak from what I have read and the fact that I change 8 ounces once a month in my 90 gallon reef and have no complaimts. If I wait much longer than that I can tell that the tank starts to so signs of stress. The signs are very subtle that probably I would even notice in my tank but who knows if it is the carbon not absorbing anymore or if It's a missed water change or both together. I use the magnum charcoal and really like it. The only way that I think carbon would increase pollutants is if a prefilter was not used or it was a very low quality carbon that some people say will release back into the tank but why would carbon release back into the tank once it is full?