I finally got one used off another member. It's the 6100 with the old multicontoller. Works great. I have a 90. I had two Koralia 4's on both ends pointed at one another prior to getting the Tunze. I am hoping to do away with both Koralia's and go with just this tunze. My question is, where is the best position for it? I see pics of tanks with these all over the place. Is it best to just let it shoot across the tank and create a steady pulsing? Or should I put it in the corner and angle it out? Or, should I still use one Koralia? My tank is SPS on top. Any suggestions?