[fambrough]

greenmonkey51 has got it right. Don't worry about it! This is not a big deal. As long as the stuff is not dying, let it grow as big as you want and cut it back when you feel like it. My refugium is absolutely packed with the stuff. I cut it back once every other month or so. I never get so much that any dies. Also, it is full of amphipods and micro starts and other small fauna. Baseball, softball, basketball; these are really inacurate and unhelpful measurements. Everything depends upon the amount of nutrients for the available and potential growth of Chaeto--and just think of the amount factors here--how is the rest of the tank processing, holding or releasing nutirents?, how much to you feed? what livestock do you have?

Let it do what it's supposed to do: take up nutirents and act as a critical part of the refugium. Also, I have to laugh at the notion that tumbling will help. Forget about it. Who on earth has actually done a controlled study to see that tumbling excellerates growth (i.e. nutrient uptake). Nutrients are gong to pass through you refugium/sump, the chaeto will grow and fix/use those nutrients. And chances are you have plenty. Keep an eye on it, that's all.