Many of us have switched to using "cheato"; short for cheatomorphia.
I believe it also does a better job than caulerpa by growing faster and therefore removing nutrients faster than caulerpa without being an invasive species like caulerpa.
There's almost always someone that brings "cheato" to the meetings and often times just looking to give it away. In fact, I'm bringing a bag of it to tonight's meeting and giving it away since the person I was bringing it for is not coming tonight.