You can't say that the population has gone down because your doing something wrong, people have work/school during the day.
Ya i can. How long have you been around...
I haven't been here long, but I was formally the co-leader of a community that was times larger then this one, and I know from experience that server populations fluctuate all the time and as long as you keep a dedicated user base you can ensure that you will always have people in your server, which is the most important thing in ensuring that your sever stays full. Why do you think I chose to come to your server out of the +30000 CS:S servers out there? It was near full. I also find that changing things on the server tends to make the population decline worse. The best thing to do (in my opinion) is to simply find a group of people and encourage them to spend a little bit more time then usual in the server, just to get things kick started. If you build it, they will come.
But, it's your server. Do what you want with it.