[chrishoney]

this is what I found on www.newart.com:

Here's the results of searching for "Aquarium pump"
http://forums.newart.com/phpbb/search.php?keywords=%22aquarium+pump%22

Several of posts mention Rena pumps which is what I ended up getting online and modifying. There are links to other posts or sites that provide step by step modification instructions.

Evidently Rena now makes a pond vacuum pump that does not need modification: http://forums.newart.com/phpbb/viewtopic.php?f=8&t=13991&p=209960&hilit=electric+pumps#p209960

There was an electric pump called VT9000 sold by Vacu Tech but it has been discontinued on Vacu Tech's website. There was also something called a BB5t surge pulsator that got great reviews but the only site mentioned selling it, also no longer carries it. So, we may be out of luck in terms of purchasing such a device.

Ooops, spoke too soon, found it: the QS-7 by Vaculogic at www.pumptoys.com. However that sucker (he-he, pun intended!) is US$569.95 and unfortunately the site lists it as sold out. I did not inquire about future availability. (Oops, spoke too soon yet again, if you click on further info they say "NOTICE: Sales of the QS7 have been temporarily suspended while we secured a new source for a particular component and finalize some new improvements; it has NOT been discontinued, and we expect to resume sales shortly. Thank you for your patience.") You can find reviews of how the QS-7 works on newart.com with this search:
http://forums.newart.com/phpbb/search.php?keywords=qs7

Hope that helps.