I added the sand at the beginning of March. I took out the bottom layer of eggcrate because it was trapping a LOT of detritus that I couldn't syphon out I had some sand from another tank that I was tearing down and figured some of my livestock would appreciate a sandbed to hang out in. I'm quite pleased with it actually. Most of my SPS have colored up more since the addition. It also gives the opportunity for more microfauna to reproduce. Yes I'm still not using a skimmer. Some days it would be nice to have one, but on such a small tank it would be obtrusive. Last night one of my Acan echinatas decided to eat one of my Favites. A skimmer would have helped in that situation. The tank is open-top and my ambient room temp rarely gets above 73. Those both play a large role in keeping the temps down. Your 29g is pretty much enclosed I assume..that would make your temp higher. Also, some kinds of powerheads heat up more than others. Maybe you could pick up some more efficient ones that could help.