Reverse Osmosis unit?

bulkreefsupply here great product and 24 gpd like the one you are looking at, you may want to upgrade to a larger unit and like stated earler you want RO/DI....

 

Here is a link to Air, Water & Ice. Many people on here have had great success with them and they are one of the cheapest places to find a new high quality RO/DI unit. You won't be dissappointed! And best of all, they are a sponsor of 3reef, so if you do inquire with them mention 3reef a couple times! The Typhoon 5 stage is a good one and it is only $150. Have them throw in a dual inline TDS meter and you have a great setup.
They are a smaller company too so you will probably have better luck getting them to ship over some of the larger companies...

 

I just got a spectrapure ro/di about a month ago and boy does it do wonders! I would highly recommend it. It's about 160 dollars on marinedepot.com and is one of the best out there.

 

Coralife units are very low end and don't get many positive reviews. lots of quality control problems and leaks plus mediocre water quality.

I second the Spectrapure, The Pro Plus at $149 complete is easily the best value in a reef quality RO/DI today.
SpectraPure Customer Appreciation SALE! 20% - 50% off

With it you get a batch tested and specially treated RO membrane which is much more efficient (read, better water quality, quantity and lower DI cost due to fewer replacements), a dual inline TDS meter, an inline pressure gauge, 1 micron prefilter and carbon block, a capillary tube flow restrictor and best of all custom blended SilicaBuster DI resin. No other vendor offers tested membranes and custom blended resins.