Thanks! I like the pronutro and dog food idea. At this stage we have oatmeal, bran & rice krispies as substrate. Reason: It keeps the crickets dry, they can eat it if they want and it soaks up some of the ... erm... cricket goo. We feed them fish food & carrots, and we clean their enclosure once a week, replacing the substrate if wet/soggy/dirty and we give them fresh water every 2-3 days, depends on how busy they've been in the enclosure.
I read about the oatmeal idea in "Tarantula Keepers Guide" and I must say, after we started using the oatmeal as substrate, the crickets stopped dying. We also remove dead crickets the moment we see it (I check on their enclosure at least once a day). I also remove the substrate on which the cricket died.