While I posted this as part of my worklog I thought I would post it here as well. Since I know there is a lot of uncertainty with buying a used acylic tank and the daunting task of polishing it. The walk thru of my tank and pictures can be found here: http://www.3reef.com/forums/tropical-fish/finally-stepping-up-big-boys-147386-2.html I did learn a few things about polishing acrylic though. First it is real intimidating but way way easier than I thought. I must work for geico cause a caveman just did it, you can too. First less than 1000grit didn't really seem to be needed unless its a pretty good gouge, and I mean a gouge. I only had one spot that 600 was needed. If you have a gouge, what I would call where your fingernail stops as you slide it over the tank, use a marker on the opposite side of the tank, this will help you look and see the reduction without turning the tank or stopping your work. Next all the stuff on the net says to go perpendicular with the scratch, definitely it only makes sense. Also always work in a left right, or up and down, don't swirl. A lot of videos also said go one direction, upgrade grit then to the other 90 degree. I went both left right over my area, then up down, and then switched. Wet sand and use PLENTY of water. I tipped the tank on the side I was working on and used 1/8 inch easy. I did also go over the entire tank with 1500grit and up just cause there was a few places where it seemed a little waving from using the 600, and 1000, so it gave much more uniform appearance. A lot of pressure isn't needed. If you feel enough pressure that it isn't simply sliding your doing enough. The harder you push the more your sanding. Although your using sandpaper the goal is polishing, not sanding. Reading some of the tech stuff it said novus 3 is roughly the same as 3000 grit. I tried it all 3 ways in different spots, just 3000, just novus 3, and both. Might just be cause of double work but both was the way to go. Speaking of novus, I bought the 8oz bottle and it was plenty. I did multiple passes inside and out on a 225g and still have 1/2 bottle of 1&3 and maybe 1/3 bottle of 2. When it comes Novus time, save your arm and get a orbital polisher. Makes sure its less than 3000 rpms though. Faster can burn and warp the acrylic. I bought one for $30 at autozone. They have more expensive and sexy ones but they are also higher speed. I almost went with a powerball like a lot of youtube videos, but the price difference was $5 and I can wash and replace the pads on the polisher. When using Novus. I found after reading and trying it that its best to go 1,3,1,2,1. Why so much one? Its a cleaner and helps to remove any reside or particles left behind. Also use a different rag for each level of novus. one rag to wipe off 3, one for 2. When using the novus make sure rag, pad whatever is wet with the product. if you let it dry its takes some elbow grease to get off. You have to be much more generous with novus 2, it just dries faster. With the polisher I was easily doing a 2ft x 2ft section at a time. With novus 2 I was limited to a 12 x 12 for best results without having to constantly add more. It just dries quicker. Also working in the shade prolonged usage too, sunlight just dried it right up. Novus 1 was hand applied with microfiber rags. Overall even with the polisher it was a lot of work, but considering I bought my tank for half of what others in the area cost based on looks I think it turned out excellent. Maybe not perfect but I could go back and readjust the few minor visible areas I have, and still might. At the same time it doesn't necessarily have to be glass smooth finish as the water will also help hide some small light scratches. Looking back at some of the tanks I skipped by in the past due to my reluctance and lack of knowledge I could had some really great deals. In the future I may start giving them more interest and attention just to polish them up and flip them. Be a good weekend project, have a few beers while I work, make a couple bucks in the end kinda project.