Why First Rays Uses RO Water

We are a firm believer in the use of pure water – rainwater, distilled, deionized, air conditioner condensate or reverse osmosis (RO) – for irrigation and misting of our plants, and have been using RO exclusively since about 1993.  This will summarize why First Rays uses RO water.

By starting with the chemical “blank slate” of pure water, and adding a fertilizer designed specifically to provide the minerals in the correct proportions at the proper pH (the Greencare Orchid Special for RO), we know exactly what our plants are getting, so can control their nutrition precisely, and adjust in a controlled manner as needed. Our plants have responded by growing larger, having more leaves, and blooming better than ever.

Further, if you mist for humidification or cooling, dissolved minerals can leave a buildup on your plants’ leaves. Misting with pure water avoids that altogether, and you’ll see that your plants really take on a glossy, clean appearance.

It was time for us to replace some of the filters on our RO system, but were concerned that the prices we see locally were excessive, and questioned the quality of the components. In the process of digging around, we learned that the markups are pretty substantial, even at self-proclaimed “discount” outlets. Fortunately, we made contact with a distributor whose entire business is quality water purification products at great prices, so have become a retailer to pass on those savings and to provide you with easy access to quality RO systems and components.

We use standard 10″ x 2.5″ sediment filters and carbon block filters, as they need to be replaced the most (we recommend every 6- and 12 months, respectively). Replacement RO membranes can be ordered, but we won’t stock them, as they have a finite “shelf life” when not in use, and want you to get a fresh one when you need it. Likewise, we can order pretty much any component you may need – filters, housing, fittings, tanks, tubing, pressure switches – whatever. Just drop us an email request and we’ll get on it for you.

The same is true of complete systems. If we had to stock them, the cost of carrying the inventory would force us to inflate the prices, which defeats our whole purpose! Instead, we will have them shipped directly from the manufacturer, ensuring you a good price on quality goods.

Click HERE to go to the RO section of our online store.

Some things to keep in mind about RO Systems:

The typical output is lower than the rated output published. The rated levels are typically done at 77°F and 65 psi water pressure. Most households’ water supply is cooler than that and at a lower pressure, so if you count on 75% of the rated output, it’s closer to reality, although water quality affects that, too. (For example, “softened” water, in which the Ca & Mg are replaced with Na via salt pellets, is easier to filter than the original hard water, and you’ll extend the life of the RO membrane.) Here is a chart to show you how the temperature and pressure affect the rated output.

They are not truly “on demand” water systems. If we have a system with a true output of 72 gallons per day, that’s only three gallons per hour, or a bit over three-quarters of a cup per minute. If you have a large collection of plants to water, you’re going to need some sort of storage tank to collect it in between waterings (plastic drums can usually be gotten from your local car wash at no charge). Systems typically come with a pressurized tank of about 3-gallon capacity, which is often sufficient (larger ones are available).

RO water is “chemically aggressive”, so it pays to use plastic or stainless steel as much as possible for all “wetted” parts. Having essentially no dissolved solids, pure water is “unbuffered”, meaning that the dissolution of the smallest amount of almost anything can significantly affect the pH. Even carbon dioxide dissolved from the air will lead to the formation of carbonic acid. I have seen a brass fitting, when exposed to RO water for a long time, have almost all of the zinc removed, leaving a brittle, porous, copper structure that is easily crumbled.

Surprisingly enough, it’s not all that expensive to use RO water either. Let’s assume you buy a 100 gpd system, replace the sediment filter every six months, the carbon filter every year, and the RO membrane and polishing filter every 2 years, and use 200 gallons a week (20,800 gallons in two years).

For the first two years, you have the purchase price plus the cost of two sediment filters (I include an extra sediment- and charcoal filters in the original shipment). So your 20,800 gallons costs around $200, or just under a penny per gallon. During each successive two-year period, you purchase a membrane, a polishing filter, two carbon filters and 4 sediment filters, for a total of $81, making the pure water cost just over a third of a cent per gallon.

Using Science & Logic to Improve Horticulture