In order to avoid any SPS related bugs, I have not added any SPS into my SPS tank ever since I started it with live rocks I bought from Greg Hiller. All SPS in the tank are from whatever encrusted on the rocks. No RTN, no red bug and no arco flatworm. So far they grow well but I want them to grow faster. I want to add a calcium reactor. Is there a hang-on-tank calcium reactor out there because I have no sump?