I have a 46 gallon bow front and decided to add a 30 gallon display refugium to the system. Will adding the live sand into the system be harmful. It wouldnt be going on top of any sand in the display just in the refugium.
I added a 30 gal fuge to a 75 and had no problems. In fact, I noticed a huge drop in phosphate and nitrates. As long as your DT is established, it will be able to handle the mini cycle