Deep substrate so the tarantula can burrow is most important. These spiders are burrowers. Your t should be fine so long as you keep the temps around 80 -85 , somewhat lower temps during night. Just overflow the water dish so that there is a moist area around the dish and the bird eater should be fine. Cocoa fiber is a great substrate. Bird eaters are high maintenance t's imo. And they kick hairs.