Injecting them with kalk will melt them before your eyes.
You need to get the big ones on your own. The peppermints will get to them, but oftentimes they are last or they just are not brave enough to do it. They will destroy the small ones, IME. Once the aips are gone, they need to be fed, just like the fish. They cannot live on detritus and scavenge. I have found that they have life spans of about 2-3 years, so they do need replacing over time. I usually order a dozen of them, keep them in the fuge until they get all of the aips in there, get them used to eating pellets, usually lose a few and end up putting 10 into my display which you never see until feeding time and then they are all out looking for dropped pellets.
They need iodine to molt and live appropriately. If you change water, then the salt mix can handle this. If not, then you will need to supplement with the right kind (there are many kinds).