I'm certainly going to explore this further. Another issue that I'd be concerned about is my siphon overflow being able to handle the added flow in the event of timing issues with the pumps being on at the same time. Perhaps a timer/switch that can only activate one circuit or the other and not both at the same time. Hmmnnn.....Not necessary a better way but far more efficient.
However I enjoy this aspect of the hobby - you can just pump in more gas or get a little more technical?
Siphon issues are easy to avoid with a short piece of air line fitted just above the water level.
I will try to get a few diagrams up tomorrow (almost midnight here)