This is a great question and one I have been wondering about too. I didn't realize that chaeto will consume ammonia too. I went with an H80 instead of the h380 and am a little worried my chaeto refugium won't "out compete" the display to limit algae growth. One possible solution I thought would be to get the Chaeto growing and taking up the phosphate and nitrate before I start lighting up the tank. This way once I start lighting the tank the chaeto will already have a "foot hold" on the nutrients and hopefully keep algae at bay. I did not consider it would interfere with the cycling though. Maybe, once you start reading 0 ammonia and nitrite and are getting some nitrate readings (after dosing your ammonia), you could start up the chaeto? This could then still be in a time period prior to lighting the tank and adding corals, but not interfere with your cycle?