Maybe because it's on the 12v line, it won't affect system stability.
I like the cap idea. Any idea what rating? Nexxo's pump draws 12 volts, and has a max power rating of 26 Watts, for a max amperage of ~2.2 amps. I know it's useless without knowing the RPM.
In the mean time, I found a spec sheet for this pump:
http://www.johnson-pump.com/JPMarine...IB-CM10_30.pdf (PDF, 20 pages)
Here's the flow curve, for all three variations:
http://www.johnson-pump.com/JPMarine...10_30_c090.htm
The good news is that this Johnson pump is the heavier model that Nexxo described, the CM30P7-1.
A quick chart gives these flow/pressure ratings:
3.3 feet @ 6.9 gpm
6.6 feet @ 5.2 gpm
9.8 feet @ 2.4 gpm
Max pressure: 5 psi: that's 11 1/2 feet, or 3.5 meters.
Max flow is 30 l/m, that's 7.9 gpm, or 474 gph.
That's a good pump!!!