I would hazard to bet all didn't die.. The change most likely threw them off. See MTS love mulm. That's why they're always under the substrate. I'd bet a few survived and the population will revive.
With the new substrate, most didn't have their normal food to snack on between feelings.
Hope this helped man. Grats on the 110G tank
you know we want a journal and pictures of it right?!
Hehe hope you're well,