is this stuff like bark chips ?
i would be a little concerned about the pac man swallowing some bark when they lunge out for food. ive been using ground coconut hsuk bedding, theres a few brands the one im using (purely because its the one my local pet shop stocks) is eco -earth. its very small particles so risk of impaction is greatly reduced
it comes in a dry block which u put in water, it soaks it all up and expands. once uve wrung it out a bit it creates a nice moist substrate that ur pacman can easily dig in, i use a good few inches and the pac man will often completly burry itself at times !! its not to expensive either 