SEO hell - the Supplemental Index

There are lots of people in various SEO forums are asking "why has my site gone supplemental?" in other words removed from Google's main index and put into a backup one. The supplemental index is only used if Google can't find enough results from their main index. That often (but not always these days) means a huge drop in rankings in Google.

Google's parallel, supplemental index used to be made up of stale pages, and particularly "dropped" pages which had links from the site removed. Since BigDaddy, we've noticed increasingly that many otherwise apparently healthy sites have pages that are falling into the supplemental index. We see this especially in low PR sites that have made major navigational changes, such as renaming pages, changing link structure and so on. It's also common in sites with little text content and have duplicate or near duplicate page titles and Meta descriptions.

A highly respected person in the SEO community said that "supplemental pages are like a cancer for a web site". In other words, once a few pages from a site go supplemental there's a knock-on effect. Maybe it's because these supplemental pages don't pass back any PR to the site, and it sinks even further causing more pages to go supplemental and so on, like a chain reaction.

In any case, it's clear that anyone doing SEO has to check their sites regularly using Google's site: operator to look for pages that are going supplemental. If you see supplemental pages, be sure to act quickly, checking their titles and descriptions to make sure they are unique and perhaps increasing the text content on those pages. We’ve also found that getting a fresh links to a supplemental page can help get it back. It doesn't have to be an off-site backlink; a link from your blog entry will often do the trick.

You should also avoid any on-site changes such as renaming pages, moving or deleting links if you have a low PR site. By all means add fresh content though.

If your site does end up in supplemental hell and your rankings have dropped considerably, we've found that a high PR7 link can get your pages indexed again within a week. Such a link would cost around $30 a month. A relevant link will be the best but might be more expensive in some markets. However, it wouldn't have to be a relevant link if you just wanted to get your pages back in Google's main index.

If you do want to make major site changes and move content to new pages then it's vital that you use HTACCESS to 301 redirect the old page to the new one. Deleting the old page and updating the link alone will probably not be enough to avoid one of the pages going supplemental.

Even if you do a 301 redirect, this may not help because of the timing. It's possible that the new page will be updated and indexed before Google has figured out that the old page has been moved. You'll then be in a situation where you have two pages with the same content, and if you have moved or renamed a large enough number of pages simultaneously it could trip a filter that would land your site in the supplemental index.

If you've had pages going into Google supplemental index, we'd love to hear your experiences and perhaps you could post a link to your site in our forum for an SEO site review with as much background information as possible.