if i see the waste laying in the sand i'll spot clean and just pick it up out of there. at least once every few weeks when i have her out i remove the water bowl and decoration then use a mesh/screen "scoop" to sift through the sand. if i notice it starting to look "dirty" even after this type of cleaning i dispose of the substrate and wash the enclosure. that goes for any foul odor as well.really when it defecates,how will i know where the feces are and when it defecated??Also during the night,it moves all around its enclosure.Why?The enclosure is 5-10 cm longer than the snake.I saw her drinking two times.Quite funny way!
a sand boa is primarily nocturnal, so it's normal to see it out at night, if at all. mine rarely comes out from beneath the substrate, normally all i see are her eyes and nose. sometimes when i catch her out at night it's when she hasn't had a meal in awhile... she might be out actively hunting. other than that, snakes definitely like to explore!
sounds like you and your companion are having a good time.