IMHO, don't bother with CeO polishing...
I used Cerium Oxide to polish out scratched in my tank, and I'd recommend using it on only the smallest scratches you really can't feel OR see - and then there's no point doing it. Cerium oxide might be great for industrial polishing, but you just can't do it very well on an aquarium. The tank
MUST be empty, and I did mine on my deck, on it's side during the summer because it was such a mess/PITA.
I think I still have the remainder of my CeO in the garage I'd sell you if you are set on doing it. My honest first-hand experience, if you can't stand the scratches, buy another tank
Here's my thoughts as taken from my reef journal:
July 3rd, 2005
The glass polishing begins! I picked out all the snails & crabs I could find on the LR and drained the water into 20g tubs I bought at Menards. I pulled the individual "clumps" of rockwork out and put them in their temp homes while I try to polish out the scratches in my tank.
I drained and the tanks water in the basement and siphoned/shopVac'ed out all remaining sand/gunk/water to move the tank. I was going to polish it in my garage but the weather was nice so I decided to do it on my deck instead. This ended up being a good move since the CeO slurry had a tenancy to spray every where while polishing. I used a 7" Chicago Electric sander/polisher I picked up at
www.harborfreight.com for $25. At that price I didn't feel bad about any wetness or powder that may get into the polisher. I made a polishing pad out of some fake leather (vinyl actually) that I got at a fabric store. I cut a square and then used some flexible wire to "cinch Tie" the pad onto the rubber backer.
I polished for about 3 hours tonight after getting everything torn apart and concentrated on only about 1/3 of the front 48"x20" pane. After quitting for the night I did an inspection, and the results are mixed. It looks better, so I'm happy about that, but I was honestly hoping for much more. I'll do more tomorrow.
July 4th, 2005
I got up this morning and got back to the polishing. Polished on and off for about 4.5-5 hours today out on the deck. It was a beautiful day. After polishing, my deck looks like someone sneezed white slurry everywhere because the polisher sprayed it everywhere. I would DEFINITELY not recommend using the Cerium Oxide with a partially full tank. If you do try it with a partially full tank, I'd make your mixture much more of a paste and use a fabric bonnet to reduce the spray from the rotation of the polisher. I ran the polisher on a pretty low speed (1-2.25 out of 10) because it seemed to spray the slurry less at low speeds. I wanted to go faster, but it worked much better to stay on slower speeds. Today I had a much harder time keeping the slurry wet, but not watery. To dry and the mixture didn't lubricate the pad and it would grab the glass randomly/violently and that wasn't good. The wind was working against me and because it was so sunny, warm & windy, I had to constantly re-wet the surface with slurry to counter act evaporation.
When I finished, I got the deck mostly cleaned up, and moved the tank back to it's stand. I didn't have time to fill it with water and check out how the scratches look. I had to head out to go watch fireworks, so I guess it will wait until tomorrow.
July 5th, 2005
This evening after supper I worked on putting the liverock and crabs/snails back into the tank. Upon inspection with the T5's on, the polishing looks to be a moderate success. I naturally was hoping to get more scratches out but I knew in reality that many were too deep to remove with the Cerium Oxide alone. I'd say I'm happy that it's better, but bummed that it's still scratched. Before polishing the scratches were intolerable, but now they are at least livable. It still didn't stop me from looking around for a 90g tank online (which is the only larger tank that will really work with my arrangement).