reef snow is coral food that people use, it comes in a plastic bottle and in my opinion is a waste of money and time as most corals will do just fine with water changes and enough light.
is granular feric oxide, it will suck up phosphates from your water. The name brand is usually rowaphos, you can get a baggie from your LFS
. As long as it comes in direct contact with the water then it will help with the algae. If you have a hang on filter or canister you can just add it in the baggies it should come with. If you have a sump you can out the baggie of it into the filter sock if you have one. thats what i do on the tanks I have that dont have a reactor to run it in.
Here is a link on GFO
. I get mine from this site cause it's cheap.
Bulk packaged Granular ferric oxide GFO for aquariums - English