I prefer the ultra because of the white color. I know its not natural, but 90% of my animals are captive bred and know nothing of nature anyways. This also gives me a better idea of stool coloration, as well as any bugs that may be in the tub, or trying to get into my snake enclosures. I also like the smoother and softer feel of the ultra.

My allergies will not permit me to use any aspen, too much for me to handle. I beleive the ultra is 50 liters and the regular is 60 liters in a big bag. I agree its highway robbery, but its for the snakes, so they get it!!! The website I listed sells the basic carefrsh for $9.99 as well.