I can only go by me experience, but I think I have only deleted one comment out the hundred or two that have been posted to my various blog articles. Unless you are being spammed by really awful stuff, consider letting your readers comments go unmoderated and reviewing them as needed.
I think not moderating comments and letting anyone reply fosters more interaction. As proof, I accidentally left my blog setting to DailyPUMA.com on the do not show until moderator approves setting. I got six responses (half were my answers), and then the comments dried up. I then realized the comments default was automatically set to moderator approval and registered users only. After I changed the moderator setting to let anybody reply, even Barack Obama, I noticed a new surge in comments to the same topic.
I think people like to read back what they just wrote after they post it, moderating comments eliminates that small joy on some blogging platforms. Now if the person doesn't know that their response is being held, until after they hit the reply button, odds are they never responded in the first place if prior comments haven't been already moderated. People tend to reply when they see that others have already replied. If you have your reasons for moderating comments before they appear, please share them here so the entire PUMA community can learn.