I swore there was no sandbox and backlinked the crap out of a domain name less then a year old. Things were going fine until I crossed that invisible line and my rankings fell like whale %$#$. I wasnt de-indexed but on or around the 10th page and knew I had enough links to be on top. I now know to go easy on a new domain. An aged domain is a different story. I read somewhere on here to keep backlinking. Dont stop. Googlebot sees a sudden stop after weeks of backlinking and you have the crosshairs on your website. So I decided to run a scrapebox campaign of 10,000 comments and also added 1000 bookmarks. Within a week of that campaign I am back on top. It was also recommended to add original articles which I also did. I deleted all my duplicate content and only added articles that were not found anywhere else and also added youtube videos related to my site using a WP plugin. Thanks BHW! The information found here is priceless.