I do know where you are coming from, but after reading all the posts and how most are convinced that live is very dangerous unless supervised.. Does this, what you have said above, mean you are feeding live, and unable to supervise each feeding? With that number I'm sure it is feasible to get a tank of CO2, you should be able to get it in any local pet fish store. Since you do an average of 30+ a week, CO2 would be able to kill all of them quickly, painlessly, all in one go. Then you can just throw them in and not worry, if they do not take in an hour, freeze them. Then feed them in the next feeding session, I'm sure they would be finished off.