substrate?

[the_frog_man]

i know i asked this befor but what should i use
i have a 6 foot chocolate pine (dont really know what it is i know its a pine tho)(srry no pics)
its a really angry snake and i am working on that by holding her 5 or 6 times a week
my question is what should i use for a substrate?
i am using reptile bark but its expensive to give her like 4 inches so she can burrow
i need to change the bedding she has shed and its everywhere
i was thinking maby beta chips or dry coco fiber but without fibers (i think those could hurt it)
also anyone in toronto who could come by and probe her or tell me what morph she is please contact me i wonna know about her and i dont know how to probe yet (dont really wonna teach myself tho mite hurt the snake) and ive never seen a pine snake with these colours




thanx froggy