When I first got my hillstreams I didn't know they liked cooler, fast water. When I found out and before I had a tank for them, I put a bubble curtain in the tank vertically with one end at the bottom of the tank and the other pointing straight up and the aerator hose attached to the bottom end. The loaches loved it as it made lots of movement straight up the tank giving them the illusion of very fast moving water moving over them, but it still left the rest of the tank pretty calm. They would hang out there most of the time letting the air and water move over their bodies. They love the algae on the glass and in time started nibbling on the algae wafers left for them at lights out.