gravel to sand

I'm changing my gravel substrate over to sand. I tried using a funnel, but the sand still ended up floating at the top, no better than before. My water also went cloudy, but that should go away in time. I scoop out the gravel with a net, then put it in a container to dump out later. I'm doing...

I need help to know how to switch from gravel to sand. I have an aquarium starter kit ten and have loaches that would seem to like sand better. The kitv has a power filter and i know a plan to make it work out. Just need to know how to swith gravel and sand without relocating my fish. Please...