Here's a link to my system I've posted before that Mike copied. I've actually been keeping up to 70 eels in this system without any problems. I keep mine in the basement as the air is cooler and it helps keep water temps down. I also do exactly what Paul said and elevate the tank so I can put a bucket under the drain and haul the buckets outside. Also, I've never worried about color of my eels as I personally can't imagine a bass coming up to an a live eel and thinking to itself "this eel the wrong shade of color I'm not eating it."
http://www.striped-bass.com/Stripert...12-post15.html