I have decent growth and good polyp extension, yet I always seem to have one piece that starts to stn from the bottom up. It usually starts a month or so after moving the piece from the sandbed to the upper part of the tank. There are no lenses on my led lights. Could it be the lights are too strong or the light spread is just not as good at the top of the tank? Could it be the water current is wrong at the top? My parameters are good, and I can often save the piece by putting it back on the sandbed, but that's not where I want my sps to be. What stress factors cause growth on the top and stn on the bottom? I only want to change one variable at a time. Should I mess with the lights or the water current?