Too much light for my tank?

I've got a 36" Finnex planted plus of my 48" wide 75gal. All I have right now are several java ferns and a couple anubias. There is a HOB filter as well with Pothos growing out of it. Light is currently on for 6hrs a day. I've noticed what I assume is a diatom bloom on the rocks and rear glass. I hear that is normal for a new tank, mine is 5 weeks. My concern is if this is too much light with too little plant load for the tank. Should I be bothering to dose ferts on this tank? The goldies poop alot so there should be decent nitrates. Opinions?