a Stenner pump is a good alternate to the old colparmer pump
http://www.uswatersystems.com/residential/systems/stenner-pumps/stenner100dm4-double-head-adjustable-output-low-pressure-pump.html
These come in dual head and are made here in USA. Replacement parts are readily available also.
Wow... This looks really cool. I didn't see any information on the site about maximum distance this pump can push/pull? This could be an awesome alternative to the LM3 that I have been looking at for my auto water change system. It should be pretty easy to program the Apex to run this for X number of minutes at various scheduled times to save a few hundred bucks over the LM3. Time to do some more research as to if anyone else is using these for auto water changers.