We tried the hands off method. In out 125, we had 45 hermits (all filling 2 inch shells and larger) and large, more than 6 large turbo snails, and some assorted other snails. Out tank had a leak and we had to do a big renovation; when the move was made the whelks were the only thing left. I am a huge over feeder and know there was no way they were hungry. They ended up about 3 inches and all four of them were relocated to someone else's house that knew the risk. I am a no mercy kind of person when it comes to whelks. It is just a personal experience, no science. But I would like to share because I wish someone had told me. Best of luck. If you like them, enjoy them. Just as long as you know them you can plan accordingly.