I Googled "instruction manual for RD..." and got this youtube video:
[ame=http://www.youtube.com/watch?v=5EFhbZaSNDk]YouTube - Part 1/3: Watergeneral RD-102 RO+DI reverse osmosis water system for Aquarium reef[/ame]
who said to go here:
FilterDirect.com Whole House Water Filters, Water Booster Pump Choices
Hope you can find what you need there, or at least some support.
(is this the right product?)