Seems like you got it figured out by now! When you get into the rythm you should be able to clear the whole tunnel between the pools before respawn. I had a rogue join me for some a well which was good fun, we cleared the whole pool(3) as well.
I found that when fearing with my back towards this spot (red arrow) they would stop just before the water at latest:
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http://imgur.com/p6rE9Ur