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Portable RO System Comparison

Besides the First Rays Counter-Top Reverse Osmosis (CTRO) system, there are others available online that are less expensive and are certainly usable for purifying water for use on your orchids, and if purchase price is your primary driving force, I urge you to look into them. The table below shows the differences between the CTRO and another popular one.

Property

CTRO

ROB

Capacity* (gallons/day)

50

50

@ PSI/°F     

25/77

60/77

Rejection Ratio

1:2.7

1:4.5

Water used per gallon of pure

3.7

5.5

Water consumption to collect 50 gallons with 40psi/65°F water**

192

521

Filter Life
(gallons throughput)

2000

1500

Annual Filter Replacement Cost***

$42.50

($85/2 yrs)

$45.00

* RO membrane capacities are stated at a specific water temperature and pressure entering them. For each degree F and/or psi your water differs from those specifications, you can expect a 1-2% change in output – warmer and higher pressure resulting in greater output and efficiency, colder and lower pressure leading to a reduction.

** For this example, for our counter-top system, increasing the pressure beyond the specification increases the output, while the lower temperature decreases it, yielding a net output about 91% of the specification. For the competitive unit using standard membranes, the decreases in both temperature and pressure lower the output, netting a reduction to about 48% of the specified output. In both units, the flush water volume does not change/

*** Filter and membrane replacement should be based upon the manufacturer’s specifications in total gallon throughput, but are often shortened to calendar-based scheduling for simplicity. For example, our filters are rated at 2000 gallons (10,000 for the membrane). If you produce 10 gallons of purified water per week, that’s a total consumption of 10 x 2.7 = 27 gallons per week, so the filters should last 2000 ÷ 27 = 74 weeks or 1.5 years.