Thanks! After looking into this more on this forum by searching and talking with Garage Flooring LLC, I've determined that my 4 gallons of Rust Bullet would be plenty to do two coats for my garage at 630 sq. ft.
I've also learned that two coats of Rust Bullet will work on a grind-ed floor, but one would have to be careful when grinding to not create too rough of spots. Hence the reason they recommend doing 3 coats of Rust Bullet for a smoother look when the concrete is grind-ed.
This put me in a dilemma. I originally was thinking of going with Rust Bullet to get a long lasting product for a lower price and simplicity. But if I will have to do three coats for a decent look, then its pushing the price above what I originally would like. And I could easily spend the same or a little bit more and get a better looking product in the end at the price for 3 coats.
So talking a bit more with Garage Flooring LLC it seems like it is possible for me to cancel my order of the Rust Bullet. If it can be canceled in time before it ships, I'll probably go with their Simple No Odor High Solids Water Based Epoxy. Plan on putting two coats of gray. 1st coat as a primer. 2nd coat with Glass Bead Additive.
I scrubbed and power washed the floor a couple of days ago. It was a lot of work. And I assume it will be a lot of work grinding the floor as well. And the same with applying the coating. So I want to have a decent looking and lasting product when its all done.
So if anyone has any tips to help me get a good finished look in the end please let me know.
Thanks for the help so far, they have been helpful. And I can't say enough about Garage Flooring LLC Customer Service. They have been great so far.