Clown Loaches will still not be happy in a 40. They need at least a 75 to start out in, then a 150 once they get larger. Why not try a zebra loach? They stay smaller and are just as entertaining.
About the cycling thing, it only said in your post that you set it up empty for four weeks. Were you adding ammonia in this time period to allow the bacteria to grow?
About the cycling thing, it only said in your post that you set it up empty for four weeks. Were you adding ammonia in this time period to allow the bacteria to grow?