If your going with live rock/live sand, you could only use one Fluval 404, with the outlet possibly split to creat currents at two areas of the tank. If this is fish only, then fill the fluvals with lots of bio media. The eheim wet/dry would depend on whether you want a wet/dry or not (nitrates build faster). Reef tank (live rock)would be around 4 times the tank size flow rate. Fish only the same or higher, IMO. The drawback with all that equipment is going to be heat. Try to get the most use out of each unit to prevent adding more equipment. Also, fish only would need the most filtration, but in a reef tank too much or too little filtration can hurt the tank. It alll depends on what your planning to stock the tank with. IMO, I would use one fluval 404, with a very good skimmer (AquaMedic Multi, Excalibur or Prism Pro) I'm assuming hangon style with no sump according to your equipment. Use live rock/live sand with the fluval loaded with good marine carbon, filter floss at the top tray and some phosphate/silicate remover if needed. *celebratesmiley*
