Hi Randy. I don't think you need to remove anything from your composter. Instead you should be fine just adding more bulking material on top of the waste. The larvae will mix it in over time, or if you want to mix it in quickly you can simply flood the unit and stir it in.
An aspect of this design is that there are a lot of air spaces in the waste due to the bulking material. One reason you're getting a harvest when you add new food could be that the activity level increases which could be motivating the mature larvae to find a more quiet place to pupate. You can achieve the same effect by flooding the unit more often which creates a less desirable environment for pupation. Every time I flood a unit I get a migration of the mature (dark) larvae. If I can see a lot of mature larvae in the lower levels of waste I'll usually leave the unit partially flooded overnight so that the mature larvae are covered. This leaves an unflooded zone for the juvenile (light colored) larvae, and a flooded zone to motive the mature larvae to migrate.
Concerning the amount of food; I have the impression that the colony will adjust to the amount of food given. On waste in a natural setting the larvae would crawl away when the food supply wasn't sufficient, but since we contain them they have to stay and wait for the next feeding. I don't worry if they have to wait a day or two to eat, or if the daily amount is less than they would normally consume. I've read that BSF larvae can eat 2 1/2 times their body weight every day, and I rarely give them that much. Having said that, if you have a local farmers market you can usually go there around closing time and pick up rotten fruit and vegetables from the vendors. I went to a fairly large one by my house last Wednesday and left with about 100 pounds of broccoli, avocados, squash, peaches and peppers.
The soggy fish food is great because of the protein content, and when I lived by a pond I regularly fed my larvae fish scraps. You don't want to overdo the fish, but any amount that they can eat within several hours will not result in bad odors or other problems.
