I needed some new features from the package deluge-web that were unavailable in the default repo. I looked into the debian package database and saw that the only package with a version new enough for my needs was in the experimental repo. There were no backports for LMDE/testing. I added experimental to my repos, apt-get update, apt-get -t experimental install deluge-web. Then I removed the experimental repo from my sources list.
I couldn't tell from the documentation whether or not there was a more "proper" way to do this. I've been told this is the wrong way to do things but I didn't understand why. If anyone could explain a bit to me how I should do this kind of thing in the future I'd be grateful, also if I have made any mistakes to my system that need reversing. On the surface, everything seems to work as it did before.