Reverse Osmosis
What is Reverse Osmosis?
Reverse osmosis is the finest filtration known. It allows the removal of particles as small as ions from a solution. Reverse osmosis is used to purify water and remove salts and other impurities in order to improve the color, taste or properties of the fluid. The most common use for reverse osmosis is in purifying water. It is used to produce water that meets the most demanding specifications that are currently in place.
Reverse osmosis uses a membrane that is semi-permeable, allowing the fluid that is being purified to pass through it, while rejecting the contaminants that remain. Most reverse osmosis technology uses a process known as crossflow to allow the membrane to continually clean itself. As some of the fluid passes through the membrane the rest continues downstream, sweeping the rejected species away from the membrane. The process of reverse osmosis requires a driving force to push the fluid through the membrane, and the most common force is pressure from the mains water supply. The higher the pressure, the larger the driving force and the easier it is for the fluid to be forced through the membrane.
Why do I need to Use Reverse Osmosis Water?
The water in our taps is contaminated with all sorts of toxic materials and these substances can be toxic to aquarium fish. Excess nitrates and phosphates can encourage algal growth, and hardness can affect the ease of controlling the pH of the water. If you use R/O water from the start, then you can add back the required amount of minerals and salts for the specific needs of your tank inhabitants.
Why use a TFC Membrane?
The thin film composite membrane can remove a larger percentage of contaminates from the water. Listed below are the typical removal percentages (actual percentages will vary depending on the exact chemistry, temperature, pressure and TDS of your water):
- Hardness : 93-98%
- Heavy Metals : 95-98%
- Ammonium : 80-90%
- Phosphate : 95-98%
- Nitrate : 90-95%
- Silicate : 80-90%
- Bacteria : >99%
Why Doesn't the Unit Produce the Amount of Water it Should?
Water Pressure : The ideal water pressure should be 65 psi. Water pressure at 45 psi will reduce the rated gallons per day production by half.
Water Temperature : The ideal operating water temperature should be 70 - 77 deg. F (21 - 25 deg.C). Low water temperatures such as 50 deg.F (10 deg C) will again restrict the output to about half.
Total Dissolved Solids : The units are rated for 200 ppm (parts per million) of TDS. High TDS can also lower product water output
Can I Use Hot Water?
No : NEVER run hot or a mix of hot/cold through the unit. Use only cold water.
Do I Need To Flush a New Unit?
The membranes are shipped almost completely dry to preserve them in shipment. The unit should be run as normal, but the first 10-12 gallons of product water should be discarded. After this, the water is ready for use. As it takes up to 10 days of continuous running for the new membrane to fully hydrate, the output during this period may be reduced from the rated output, but the product water is still properly filtered and can be used as normal.
What Do I Need To Do If I am Not Using the Unit Permanently?
The membrane is extremely delicate and must not be allowed to dry out once hydrated.
For short periods of non-use, the membrane can remain installed in the unit, but the pipe work must be fitted in such a way that water is always trapped within the membrane housing so it does not dry out .
For longer periods (say 3-4 weeks) of non-use : the membrane should be removed from the unit and stored with 2 tablespoons of product water in an air-tight, sealed plastic bag, and placed in the refrigerator. DO NOT ALLOW TO FREEZE. After re-installation, the first 1-2 gallons of product water should be discarded
The Unit Seems to Produce a Lot of Waste Water
Unfortunately, Reverse Osmosis units only produce about 1 gallon of product water for every 4 gallons used. So 3 gallons of it goes to waste (Figures are approximate). So if you are supplied with metered water, so may need to consider the implications, and hence the cost, of R/O water production prior to making any decision.
How Long Does the Membrane Last?
Used under average conditions, the membrane can filter about 25,000 gallons of water : or about 3-5 years of service.
However, TFC membranes can be damaged by Chlorine, so proper maintenance of the sediment and carbon pre-filters is essential.
(We are indebted to QualityPure Reverse Osmosis manufacturers for permission to use the information contained above)