I hate my acrylic 240 because of the coralline buildup I constantly battle. I tried the sanding route and the plastic blade route with no success. I finally just let it go and decided to sell the tank and shell out the cash for a glass 240.
Carl from Reef Solutions convinced me to keep the acrylic and he'd come over and show me how to maintain it. After a major scraping and a professional polishing job, I can finally see in my tank again. He took out a gouge in the front that had been there from the beginning. And also taught me how to do it myself without gouging it. Turned out great. Thanks Carl!
I still have some scraping to do on the back.
Here's what it looked like before:
Here's what it looked like after: