I have been raising boas for many years. My largest was a female BCI which reached just shy of eleven feet before I sold her. I kept her for over a decade. I have experimented with a bizillion different substrates. I just recently aquired my first Argentinian, and the Vet tells me she is gravid.
Recently I stumbled onto something which worked well for a couple years with a columbian, and so far is working well with my Argentinian. You won't believe it, but I swear it's true. It seems that boas don't like to mess up their enclosures. They will use a litter box! Heres how I found out.
I custom build all my cages, Always have. One day I decided to offer a greater thermal gradient by cutting a hole in the bottom of my boa cage. The bottom was already enclosed. It's an old department store display case with a pedistal/box underneith. This part is cooler than the top. I now have a heat tape on rheostat, because she spends so much time down there. Any way, without fail, for the last year and some months, two different snakes have been in that enclosure, and both will only crap in the lower hide box. So I went to wal-mart and got a litter box, and made it fit that area. No substrate is needed there. The snakes go down there, use the litter box, and then come out when they are done. There is a door I can open for cleaning, I just slide the litter box out, clean it, sterilize it, and put it back. NO MORE DAMN SUBSTRATE!!! The top part of the cage is carpeted with inoor/outdoor green carpet, and very nicely decorated. This has made the whole cage cleaning issue a BREEEEZE!!! I highly recommend it, if for no other reason, than to get more people to experiment, and see if they can confirm my findings. I will be happy to snap some digipics and e-mail them to anyone interested. I have'nt figured out how to post pics here yet. Thanks for reading, and good luck!
Tony.