Hi Tom, I found your link showing your tank specs. Most people reccomend a flow of 20-40 times the size of a tank. So for your 250 gallon tank, you should have somewhere between 5,000 - 10,000 gph in your tank. 2 mags at 1800 gph and 2 koralia 2's at 600 gph has you around 4800 gph. Becasue you have large fish who love to swim I would recommend being on the higher end to give them exercise and to keep the bioload suspended so the skimmer can remove it. If you take Mark's advice and get the wavemaker off e-bay you can purchase 4 maxi-jet mods here:
http://www.jlaquatics.com/phpstore/s...ID=wp-mpsf1600
this should give you some really nice flow at a relatively cheap price.
HTH
Kevin