I've (temporarily) been forced to move some fish into my mixed reef tank, and they are putting a strain on my biological filter and have raised my nitrates to around 20. I've done multiple 50% water changes, but the nitrates are elevated within a few days. My softies seem to be doing well, but I have noticed some color changes in my SPS as well as a decrease in polyp extension. As a result, I need to move them for a month or so until I can find the fish another tank. I have a 10 gallon tank that I can move my SPS into for the time being, but it is empty at the moment. I also have a spare light, powerhead, and an old HOB filter with some carbon, and even an old, crappy, skimmer. My plan is to take a small amount of sand, a few pieces of live rock, and the SPS and place them in this tank for the time being. I imagine the tank will have a mini-cycle, but I'm hoping this will not harm the corals as much as having them in a tank with nitrates consistently at 20 ppm. Is my thinking correct on this, or am I doing damage by putting the coral in a tank that is not mature and exposing them to a mini-cycle? Any input would be appreciated.