Each of my two new systems will be set up with two Arctica 1/3 HP chillers (so, four chillers total). Each system will have two identical, redundant return pumps (it is looking like these will be Iwaki MD-55RLT - 1104 GPH pumps). I hate running extra pumps just to pump water through chillers that aren't even running most of the time. So... What are your thoughts on the possibility of putting the two chillers in series? Alternatively (and this is seeming like a better idea), what are your thoughts on running the outflow from each return pump through a chiller on the way to the tanks? It seems that with, say, submersible pumps, running the return line through the chiller might not be the best idea (would reduce flow too much maybe), but with Iwaki pumps I'm guessing the flow reduction would not be so much of a problem. Thoughts?