Crystal Quest Reverse Osmosis Water Filters

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Reverse Osmosis Water Filters can remove many contaminants not addressed by other filtration methods (except distillation) such as nitrates and fluoride (except special fluoride filters or filters incorporating fluoride specific media (such as SIR-900).   It will not remove all contaminants from water as dissolved gases such as dissolved oxygen and carbon dioxide. Radon is a gas that is not removed by the RO membrane, but it is removed by the activated carbon pre- and post filters. 

The ability of the RO membrane to filter out contaminants is generally expressed as a rejection rate (percentage of contaminant rejected). The rejection rate of an RO filter can depend on a number of factors, such as water pressure, temperature, the pollutant concentration and chemical properties of the pollutant.  Membrane type and operating conditions will also affect the degree of pollutant removal. That said, RO is effective in eliminating or substantially reducing a  wide variety  of contaminants.  It will allow the removal of particles as small as individual ions. The pores in a reverse osmosis membrane are only approximately 0.0005 micron in size (bacteria are 0.2 to 1 micron & viruses are 0.02 to 0.4 microns). Reverse Osmosis  has the greatest range of contaminant removal among  filtration techniques commonly used to treat household water and perhaps the only one that will remove things as small as bacteria and viruses (except distillation).

A specific amount of pressure is necessary for separation of purified water and contaminants. This required pressure is based on the type and concentration of contaminants in the water. For example, producing purified water from sea water requires more than ten times the applied pressure than regular tap water requires. Supplying even more pressure to the contaminated water than is required provides better separation and a higher production rate. Doubling the net pressure across a membrane more than doubles the output flow rate of purified water. It should be kept in mind that home water pressures typically vary significantly; thus changing the efficiency of the unit. In addition, water production and rejection rates in some units decrease as the storage tank fills since this increases pressure on the purified water side of the membrane. Thus, the tank should be emptied daily and sized accurately to fit the water use rates for maximum benefit. 

Water temperature will also influence the production rate of purified water. The higher the water temperature the better the production rate. A drop in temperature from 75 degrees to 45 degrees cuts the production of purified water virtually in half.  

The separation of ions with reverse osmosis is aided by charged particles. This means that dissolved ions that carry a charge, such as salts, are more likely to be rejected by the membrane than those that are not charged, such as organics. The larger the charge and the larger the particle, the more likely it will be rejected.  Thus, RO is less effective with VOCs (volatile organic chemicals) than carbon filters.  However, all the RO units have carbon pre-filters and post-filters.  

One important factor is the membrane type. The RO-Ultimate uses a TCF  or Thin Film Composite membrane and the Portable Reverse Osmosis system uses a CTA or Cellulose Tri-Acetate membrane. 

TFC membranes have superior strength and durability as well as higher rejection rates than CTA membranes. They also are more resistant to microbial attack, high pH and high TDS (total dissolved solids). They can be used with any water, including non-chlorinated well water.  The  TFC membrane is a synthetic membrane that has an over-all removal percentage between 94-99%. TFC membranes cannot come into contact with chlorine. Chlorine will destroy a TFC membrane.   Therefore TFC systems are ALWAYS equipped with a carbon pre-filter that removes the chlorine.  A TFC membrane uses a carbon pre filter before the membrane to remove the chlorine and then another carbon filter after the membrane to "polish" the water just before dispensing.  TFC membranes have a higher rejection rate of many chemicals than CTA membranes and the extra carbon filter additionally removes more contaminants than the single carbon filter used in CTA systems.  TFC membranes will typically last 3 to 5 years. 

CTA  membrane is an organic membrane.   CTA has a typical removal percentage of 86-94%.  Since the CTA is an organic membrane, it needs chlorine to protect itself from damaging molds and bacteria. The CTA membrane MUST be run with chlorinated water and cannot be run on non-chlorinated water systems (wells).  CTA membranes typically use a sediment pre-filter and pass the chlorinated water into the tank (Chlorine is a dissolved gas).  The carbon post filter then removes the chlorine.  CTA membranes typically last 18 to 24 months. 

A major disadvantage of RO, in particular, is the large amount of contaminated wastewater generated. This can be as much as 50-90% of the incoming water. The amount of wastewater generated is largely dependent on the pressure difference across the membrane. The larger the pressure difference, the smaller the wastage rate.

RO systems, as with all other home water treatment devices, require regular maintenance and replacement of various components for continued good performance. Pre-filters and post-filters need to be replaced on a regular basis. The length of time between changes of pre-filters will depend on the water quality, especially the concentration of solids. The contaminant concentration, membrane rejection percentages, and efficiency of activated carbon removal are the determining factors for replacement of post-filters. RO membranes should typically last for 1-3 years depending on operating conditions, membrane type and pre-filter performance. Unfortunately, it is difficult to know when replacement of the various components is necessary.

Some typical removal rates for an RO system are:

5 stage Reverse Osmosis with Booster Pump. Crystal Quest Reverse Osmosis water filter with the Booster Pump is the perfect 5 -stage reverse osmosis system for the do-it-yourselfer on a budget.  The RO-Ultimate comes with everything needed to install this system with complete easy to follow instructions. 

This 5 stage filtration system produces 50 gallons per day, has a 3.2 gallon/12 liter storage tank, and comes with a long reach faucet and booster pump.  The three pre-filters are 1) 5-micron sediment pre-filter cartridge  2) an activated carbon pre-filter cartridge , and 3) a carbon block pre-filter cartridge.  The RO membrane is a 50 Gallon per day TFC Reverse Osmosis membrane.  The 2 post-filters are an inline GAC filter and a 5 stage Crystal Quest KDF/GAC cartridge.

Price $310.85

Portable Reverse Osmosis Water Filter is a high capacity, high quality, portable, 3 stage countertop unit that hooks up to the sink faucet.  Great for homes, apartments, offices, recreational vehicles and laboratory use.  All hardware is included.

This compact unit has an amazing 50 gallon per day capacity. Stage 1 is a 10: RO granulated carbon cartridge as pre-filter.  Stage 2 is the 50 Gallon per Day TFC Reverse Osmosis membrane. Stage 3 is an inline GAC cartridge

Price $142.25

Replacement Cartridges for the RO portable

10" R.O. granulated carbon cartridge (You need two)

Price $ 16.95

TFC - 50 gallons per day TFC membrane

Price $39.00

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