Always try natural methods first. Chemicals are a last resort and a bandaid that doesn't fix the underlying problem.
Also, when doing water changes, try to remove as much of the algae as you can. Some of that looks like green cyano.
https://www.thesprucepets.com/cyanobacteria-blue-green-algae-1378628
10 teaspoons of gfo for my system is good? its a 60G tank but probably 50G of actual volume