Woody, I was thinking of a coil that was just like your single and not doubling them up. Did you measure flow rate through just one of the coils? I'm curious to see how your new idea of feeding from the middle goes. I would expect that you feed from the pump to a Y or T fitting to go to the two coils. I'm thinking that that would then divide you flow rate through each coil and not help. Maybe a smaller diameter tubing is needed to increase velocity over the longer distance. Keep us posted on your expierements and results.

MikeR