Is it possible to use search api indexs together? I'm trying to create a search page for forum topics. Forum topics however are both posts and the comments attached to them, unlike other content the comments and actually posts are just as important to search.

I have an index of all forum posts and one of all forum comments. I'd like to be able to have both searchable from one page. Maybe even if it's possible then I'd like to have one index that handles all of them. But if that is not possible then is it possible to combine two index's in search api into one page search?

I'm not finding anything on this so far, but will keep looking. If I find something before I get an answer I'll post it here.
Yes, you need to used the Search API multi-index searches module.


  This module is an addition to the Search API module which allows users
  to search on several indexes at once.
  
  When the module is enabled, you'll get a new Views base table where
  you can search all enabled Search API indexes at once. Performance
  might suffer, though, if not all indexes lie on the same Solr server
  (or other backend server that supports this feature).
  
  Please note that, since multi-index searches aren't supported
  explicitly by the Search API, most other Search API add-on
  functionality (facets, autocomplete, saved searches, search pages,
  etc.) won't work with searches created with this module.


There is also a sanbox project that allows you to combine Search Multi Index and Facets.