Ray - from Tunze:
"The "Nano" model series has been designed for the use in reef biotopes up to 200 liters (52 gal.) and is gentle to the plankton in operation. The DOC Skimmer 9002 removes up to 80 percent of organic waste matter, such as protein and cellulose, from the aquarium water. Very little space is required in the aquarium, and its handling is very easy. On account of their construction, these models are particularly quiet during operation. On account of the high demands in stony coral aquariums, this skimmer should be used only in aquariums with about 100 liters (26 gal.) of water. Mixed aquariums or soft coral aquariums up to 200 liters (52 gal.) can be set up without any problems."
The 250 would be a bit beyond the rating on the 9002, especially with a lot of SPS. With (I think?) more space in the back of the 250 maybe there are other skimmer options that might be acceptable? I don't really have an answer, other than something like the Euro-Reef. If you really like the looks of the tank, and wouldn't mind something sticking up in back, there are probably several options.
