New Calculator Available
You may have noticed your RO or RO/DI system produces less purified water during the winter when tap water temperatures decline. Feed water temperature, and feed water pressure (usually expressed in pounds per square inch, or psi) are the two variables that most affect this production. The concentration of impurities in the feed water also affects production.
FILMTEC® rates the production from their 50, 75, and 100 gallons per day (gpd) membranes (± 20 %) under controlled conditions, with 250 ppm TDS softened feed water at 77 degrees Fahrenheit and 50 psi, with 15% recovery (or about a 5:1 waste to permeate ratio).
Colder water, water under less pressure, or harder water (higher TDS) will reduce the amount of water purified by the membrane. Because reef hobbyists typically don’t have means to modify the amount of dissolved solids in feed water, discussion of system production often focuses on the variables we can control: temperature and pressure. There are various means to modify feed water temperature, and feed water pressure can be enhanced with a booster pump.
To answer the question “How much permeate should my system be producing?” Buckeye Field Supply announces the availability of a new calculator to estimate the production of purified water from systems utilizing 50, 75, and 100 gallon per day (gpd) Filmtec reverse osmosis membranes. The calculator allows input for water temperature in Celsius or Fahrenheit, and water pressure in psi (with an assumed feed water dissolved solids concentration of 250 ppm), and provides an estimate of the expected production of purified water expressed in gpd. If the production from your system is substantially lower than values produced by the calculator, the membrane may need to be replaced.
Russ @ BFS
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