Sorry to hear about the losses, it happened to me with a 90 gallon tank with large Ryukin and Telescope goldfish in it. You did a great job setting up the auto feeders and it seemed to work out perfectly. I was at a fish club meeting and the owner of a LFS in Manhattan, his name is Chi, he said the most common reason for people losing fish is when they have other people feed them. They almost always over feed and kill the fish. Enjoy the swap meet.
Sorry for ur losses. Snails are very usefull in case some fish die in the tank in ur absence. They eleminate some harmfull bacteries may effect your other fish. Once i had to use this kind of feeder it was okey for that long period. They are really good. You got beautiful fishes especially the red kois 👍👍👍
