personally i dont think you need a air stone if you have a trickle filter and you have enough water movement. still water on the top is not nice, if your surface water is moving thats a good thing, if not buy an air stone. i dont like the look of them but thats just me. i like natural things and ive never seen an air stone in a pond, ocean or river....but hey thats just me.....if you like them, do it..