Yes wrightme43,
nitrate is negatively charged. I would expect an ion-exchange resin to work pretty very well here. However, an RO unit will filter about 90-95% of the impurities out of the water and save your DI catridge. Without an RO unit, your DI unit will become de-activated about 10 times faster and you will therefore be buying them 10x faster. Thus I'm not sure you will achieve your goal of saving more money this way. Water is generally cheaper than an RO cartidge. Also, I would not suggest to buy a high end unit whatever you do. Please understand that there are only a few companies that make RO membranes. There are more companies that make DI resins and cartridges but still not that many. Most companies selling you a unit are buying their cartridges wholesale. The unit itself is just a series of holders and gaskets to hold the cartridges. Look on the internet...you can find many assorted 3-6 stage RO/DI units for under 150$. These are just as good as a high end unit costing 350$ or so. If you want more pure water, go for less Gallons/day. A 25 G/day unit will give you about 95-99% pure water, while a 100 G/day unit is only about 80-90% or so roughly depending upon your water pressure and local tap water purity. I myself use a 100G/day from E-bay and have no problems with it. Also, please understand that the company I work for is one of the largest sellers world wide of RO membranes and other home and industrial filtration equipment. We sell 100's of millions of dollars worth each year. Any unit you buy has about a 1 in 2 or 1 in 3 chance of having our membranes in it, regardless of what it says on the lable as we are one of the two major primary manufacturers. Don't get sucked into the higher cost is better game here.
Sincerely...Collin
