About 4-5 hours. Started with the #3 by hand for the deeper scratches, then used a 6" palm polisher for the #2 and #1 compounds.
I do shims under each vertical support. Overkill always works too. Nice start on the BG.
Went ahead and spaced the shims every 6". May be overkill but figure better safe than sorry. Tank is 100% filled now so leak test in progress (fingers crossed If all goes well then I'll drain it down in a few days and start working on the 3D background for it.