Reverse osmosis, also known as hyperfiltration, is the finest filtration known. This process will allow 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. It can be used to purify fluids such as ethanol and glycol, which will pass through the reverse osmosis membrane, while rejecting other ions and contaminants from passing. 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 cross flow 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 a pump. The higher the pressure, the larger the driving force. As the concentration of the fluid being rejected increases, the driving force required to continue concentrating the fluid increases.
Reverse osmosis is capable of rejecting bacteria, salts, sugars, proteins, particles, dyes, and other constituents that have a molecular weight of greater than 150-250 daltons. 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.
If you have a reef aquarium or even a standard marine aquarium, this is the preferable method of water exchange. This process however is not cheap, it takes many gallons of tap water to make a single gallon of RO water. You do not have to spend a lot of money on an Reverse osmosis system, in fact, you can buy inexpensive units at your local builders supply outlet.
On our commercial installations, we use several units which are connected to a large polypropylene holding tank. This tank is connect directly to the aquarium and used for top off or water changes. You can even add salt to your holding tank using an inexpensive submersible pump to circulate the water and pump to your aquarium. If you have the funds, most of the maintenance can but done automatically and surprisingly accurate.
If you would like more information on automated systems, please feel free to give us a call.