If the albino and pastel were already small when you got them, then they should catch up with proper feeding (which you're giving them - one small once a week). That tub setup and temps should work perfectly. I'd be that if you held off weighing them for a couple of months, you'd be amazed at the dramatic amount of weight they'll probably put on.

I'm glad you specified that the pic is from when the leos were in there, or else I'm sure someone would have asked why you are trying to feed mealworms to your BPs!