Carbon

Is it alright to have a filter bag with carbon in it around the intake to your refugium?

 

Sure, personally I like mine under an overflow but any where works.

 

What exactly does the carbon do?

 

In my experience it makes the water clearer which helps more light get to the corals. It removes dissolved impurities from food you feed, fish poo poo or liquid coral foods that will cloud the tank or give it a yellow or green tint. I like to run mine 24/7 in a reactor...you can run it anywhere you want you just want to make sure 90 percent or more of the water flows through it and if it does get clogged it doesnt block an intake or output.

 

+1

Carbon will also absorb inorganic impurities, and toxins (like from coral chemical warfare, etc.) that a skimmer cannot remove. Some may argue that it's not necessary, but in my 38 years in SW aquaria, I've yet to find a valid reason not to use it.

 

I have a home made filter in my refugium output and I placed it in a filter bag there. Thanks for the help.

 

Should be okay, may actually be better to have the filter bag on the other side, as the water is flowing out of the refugium. This is just because algae can release carbon and organics and perhaps toxins (especially if it "goes sexual" or dies off), which may be detrimental to corals. However, Many people don't do so and seems fine, better to have it somewhere.