So I have both Grape caulerpa and Chaeto in my refugium. Since I set the tank up I've had both in the refugium and my phosphate level was a fairly constant .25 and a 0 nitrate reading almost the entire time.
With those parameters I was getting approximately 1lb of grape caulerpa growth per month Which I really had absolutely no issues with
Recently, I picked up a birdsnest, a rescue acropora, and another rescue birdsnest. At the same time I decided it was time to add some phosphate media into the tank so I added it into a HOB
filter and let it run which quickly finished dropping my phosphates down to good levels.
In the three weeks I've been running the phosphate media my grape caulerpa has almost completely stopped growing. However my cheato has quickly taken its place and has completely packed my refugium full. What started with approximately 1 oz of chaeto has grown into approx 9 ounces or so in that time.
It's acknowledged that caulerpa is a bigger consumer of nutrients but it is good to note that its growth falls short in low nutrient systems when compared to chaeto.