Eheim makes an air diffusing attachment for output of the 2217 model which I've been using for a bit. I'm not sure how effective it is, and information seems a bit difficult to find anything concrete but it might be something you might consider DIY if you wanted some peace of mind. That said, it certainly does add bubbles I'm just not actually sure how effective it is vs how effective it would be on a tank that large. Just a random idea.