I'm using the Tunze Nano Wavebox for it. One of the better investments on my tank. And the moment I dialed it in, my RBTA went from really long and stringy to thick "bubbles." Even though I know its unknown to why they sometimes bubble and don't bubble up, I really do think that flow is a huge factor. In a friend's 230g his RBTA is about 15" long, had gorgeous bubbled up tips and the coolest pattern of pink swirls in them. We changed out the rock work and the moment the flow changed the bubbles stopped and have been stringy ever since.