you can run mag drive pumps external im running a mag 7 on a closed loop now and it's running fine.i also heard the same thing that you can't run them external and someone on this board talked to danner mfg and they said it was ok.i think it might have been troy [pro_builder].im looking at my mag 7 box right now and it says [quote] completely submersible,use in or out of water.hth.there website is
www.pondmaster.com
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120 gal/in wall tank/starboard substraight/2 250 watt 10k xm metal halides/ 4 55watt 03 actinics/150lbs lr/scwd on return/scwd on a closed loop/aquaclear aquatics 200 pro wetdry w/skimmer.
ask all the questions you have if we cant answer it we'll make up some thing. remember patience is the key to a kick ass reef.
dave.