HCA: Hermit Crab Association

So my isopods decided I have a perfect breeding tank and now I have a TON LOL. That's not really a problem since my two bugger crabs like to eat them, it's kind of a win win, they self regulate and repopulate Lol. Anyways, as my crabs are getting bigger, I want to add more substrate but there is no possible way to get all the isopods out of the tank. I would like to assume they will be fine if I add more and just climb their way up but I wanted others advice. Obviously, I couldn't mix it wrll with the old substrate like normal. It's only a few months old and still in ok condition. Thanks!

The isopods should be fine. I remember having isopods in my tank and fluffing up the substrate, they never had any problem in re-populating the tank. Plus it was common for me to find a moulting isopod buried an inch into the substrate, so I sure they could dig their way out if they want to.

Given how deep I sometimes find them in my garden, I'm sure they'll be fine.