Roger I have followed the skimmer thread a while and think a 3140/2 may be right for my tank. Did I understand this skimmer can be modfied to the new open loop design later if desired? Do you have a feel for the approx. cost for this and how much bigger a foot print in the sump? The calcium reactor fits perfect is the foot print of the 3140 the same? Is the clear riser tube on the skimmer removable for cleaning or just the collection cup? This question really revolves more around ease of getting the skimmer in and out of the sump as the sump wall are tall thus low clearance. If the comline box is the same as the calcium reator and the riser is removable this will wok great. Regards Bill