Neither. Just use ChemiClean it'll be gone in 3 days. Cheap and affective. Don't overfeed and vacuum sand bed w each WC and blow off detritus of rocks. Add flow maybe to the areas of cyano to not get it again.
As far as GFO or pellets. I have a solana 34 w GFO. I can't get my nitrates down so I'll be trying all in one bio pellets soon.
You don't even need a skimmer for that size tank. I would run GFO/Carbon in a bag and just keep up with weekly water changes.
Most people will tell you NOT to use chemicals to get rid of it, but I have personally used Chemi-clean before, along with a 3 day lights out and it worked with no ill effects.