Loaches don't like to be moved around, and when I added my last group in with my existing colony it took a good 6 weeks or so for them to settle in to their new home. It also seems that the larger they are, the longer it can take for them to acclimatize to their new surroundings. I suspect that yours will start coming out in the daytime soon enough. I use Colombian Tetras as dithers, and they have worked out well.
BTW - clown loaches do prefer low light conditions, but most will adjust to brighter lighting over time.
HTH