James's 60 Gallon Cube Reef

[daplatapus]

The little grape looking things on the vine is Grape Caulerpa. It can be invasive and a bear to remove once established. The little roots get into your rock.

GFO - Granular Ferric Oxide - Used to remove phosphate from your water. Usually used in a reactor and changed out ever month or so. Some use it in a sock and allow water to passively flow through it in their sumps. If you have algae in your tank, you've probably got phosphates. But you don't want to strip it all as corals and things in your tank need it to some extent. It's finding that balance that's tricky.

Carbon - again either used in a reactor or sock in your sump. Used to remove harmful toxin's released by corals etc when they get stressed. Also good at removing some chemicals. I don't think people run carbon all the time, I don't, just when something goes wrong and you're trying to maintain water quality till things settle down.

That's a VERY brief, general answer. Lot's of reading can be done on both.