Believe me, I had thought this exact same thing as well. Even just a tiny amount caused issues for me... Also, be aware that it took about 2-3 weeks to see any improvement once GFO went offline. I still lost a few colonies with burnt tips too as they couldn't fully recover. Newer frags are doing very well though, and the existing colonies that pulled through.I do use GFO but 1/3-1/3 the recommended amount. I honestly have not changed it in a 1 1/2 to 2 months. I turned it off a couple nights ago to see what happens.
I'd recommend you snip the algae covered tips which will encourage growth.