Buffing is a lot of work, even with a drill. I had a friend who spent 3 days (about 4-6 hrs a day) on a 150gal tank and it looked okay, but IMO not acceptable. It all depends if you can tolerate a tank some scratches.
That's ridiculous... I did my 8' 450g , hand sanding and cordless drill buffing, in 2 days/ 3-4 hours a day! Have also done 3 130g/ 48"x24"x27"h (1 tank is over 20 yrs old) in even less time and they look great!
Divide the tank into smaller 'quadrants', if possible position tank so that you are working down/not sideways, WET sand with at least 8 diff. grits, when 1 panel is complete, then use #3, then #2 Novus liquid buffers.
I suggest starting with a smaller side panel first, inside (and out if necessary) to see how well you are doing, and decide what adjustments/improvements you must make.
It's hard to see progress/results until you have gone thru all 'stages' of sanding and buffing, but if you're willing to put the effort in, it should work out fine.
Depending on the size of the tank and how deep the scratches are, anticipate a lot of time to do the job the right way.
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Divide the tank into smaller 'quadrants', if possible position tank so that you are working down/not sideways, WET sand with at least 8 diff. grits, when 1 panel is complete, then use #3, then #2 Novus liquid buffers.
I suggest starting with a smaller side panel first, inside (and out if necessary) to see how well you are doing, and decide what adjustments/improvements you must make.
It's hard to see progress/results until you have gone thru all 'stages' of sanding and buffing, but if you're willing to put the effort in, it should work out fine.

Rather than calling me ridiculous, chill and read my entire post, you can probably understand what I'm trying to point out!
Tatuaje08, How would you go about doing scratch removal on glass? Just curious for future reference.