They are a very low end drinking water system, not in any way comparable to a reef quality RO/DI.
Look at much better systems in the same price range or less such as the $130 90 GPD system from www.spectrapure.com , the 75 GPD Premium system from www.buckeyefieldsupply.com for around $169 or the Optima series from www.purelyh2o.com in several models in that same price range. No comparison.