Reverse Osmosis and Discus Fish

A Brief Look At Aquarium Filtration

The primary purpose of aquarium filtration is to remove harmful by products produced by the fish. This process is termed nitrification. Ammonia is given off by the fish and food in the aquarium. Ammonia is harmful to tropical fish. In the aquarium filter specialized bacteria consume ammonia as a food source. Their byproduct is nitrites, toxic to discus. However a second type of specialized bacteria consume nitrites as a food source. Their end product is nitrates. Nitrates are not as toxic as nitrites, but do cause problems in fish. Nitrates are removed by water changes. For more information on discus aquarium filtration and nitrification visit the discus care guide page.

Water changes are done to remove nitrates and impurities from the aquarium water. High nitrates indicate an aquarium in need of more frequent water changes. Water changes is where the reverse osmosis water comes into use.

Reverse Osmosis is a method of filtering water by pressing the water against a semi-permeable membrane that sits inside a filter housing. This membrane allows water molecules to pass through, but not others. Minerals, trace and other elements are removed producing pure raw water. This water is too pure for aquaria use without reconstituting. Marine hobbyists add salt mixes containing all the essentials. Soft water aquarists must also add trace elements and minerals back to the water to make it suitable. Pure ro water is not suitable for discus fish or angel fish.

The water passes through several filters, each representing a stage.
STAGE ONE : Water enters the filter through a micron sediment prefilter. This removes small particulates, bacteria, cysts, spores and grains of sand.

STAGE TWO : The water then passes into the carbon prefilter. This removes chlorine, toxins and chemical impurities along with any pipe cleaning additives used by the water department. It is crucial that a high quality carbon block is used for this stage. The best carbon blocks available today are capable of removing chloramines, a mix of chlorine and ammonia that many municipal water suppliers now use as disinfecting agents in tap water supplies. A reverse osmosis filter is only as good as the components making up the system. Osmotic reverse osmosis filters use the highest quality components available.

STAGE THREE : Next the water passes through the membrane to complete the filtering process. There are numerous grades and types of membranes available. TFC membranes are thin film composite. They are suitable for well water or city tap water. Chlorine can damage them but a good carbon prefilter solves this. In the past distinctions were made on membrane application based upon whether it was to be used on a chlorinated tap supply or untreated well water. CTA membranes, cellulose triacetate, can handle chlorine but they are more costly, less efficient and not necessary. The vast improvement in carbon block quality will render these obsolete. The best membranes on the market are tested and certified by the NSF and approved by the FDA for drinking and food use. They feature high removal rates of silicates, phosphates, nitrates and other compounds. Contaminates removed by the filter are discarded through tubing going into a drain. The "reject" brine water used in this is the equivalent of taking a couple extra showers per week or washing the car. The reject water is not similar to turning on a faucet. It is a small stream going through 1/4" tubing. ro is much easier to use and more economical than the other two methods of water purification which are deionization and distillation. ro water can be "polished" with di as an extra stage after the ro. for sensitive reefs requiring totally pure water. In this case the di filter is not quickly exhausted as the ro membrane has done most of the work. Pure product water (ro water) is delivered through tubing coming from the membrane. It drips out at a rate determined by the size membrane. A 50 GPD ro filter will produce close to 2 gallons per hour under ideal conditions. Performance is based upon water pressure, supply water temperature and system design. Osmotic reverse osmosis filters are designed for high efficiency. In low pressure situations a booster pump is used to increase pressure. The ro tubing coming from the membrane can be attached to a float in a sump or barrel, to the ice maker on the fridge, to a drinking water tank or any combination. An auto shutoff valve is used in this. You can tee off to as many devices as desired. However this must be configured properly. When adding floats on a drinking water system special considerations arise which must be addressed properly including the addition of a a check valve to prevent back flow from the barrel. When using a float, the auto shutoff valve must be used to prevent harmful back pressure on the membrane. Without a shutoff valve the filter must be manually turned on and off for each use by turning on the cold water supply.

 ADDITIONAL STAGES : The ro filter may have a di filter on it, which is another stage. This is referred to as an rodi filter. Some have multiple carbon prefilters which represent more stages. With the new improved technology of the manufacturing processes, the best carbon blocks today remove all components of chloramines, which was unheard of just a few years ago. Osmotic ro filters use the highest grade of carbon block available today. All municipal water supply companies will be using chloramines if they are not already using them. Chloramines are chlorine and ammonia used together to disinfect the tap water. Some generic brand ro filters add unnecessary extra stages as a selling point to sound impressive and boost refill cartridge sales.

First step-The filter is attached to the tap water supply. Most ro units feature a  diverter that will attach to any sink in any house.  Osmotic reverse osmosis filters easily attach to any sink in the house. To operate the filter, you turn on the cold water and pull a small lever on the diverter. This sends the tap water to the unit. Simply turn off the water to stop the operation. There are several options for attaching the tap water supply to the filter. A garden hose fitting or saddle valve may be used.

Second step- Place the brine reject tubing into the sink drain. This carries impurities down the drain. If attaching the filter to a saddle valve on the cold water supply, the brine reject line can also be attached to a saddle valve on the drain line.

Third step-Place the ro product tubing into a barrel or container to hold the water.  If using an auto shut off valve, attach the float at this time.
Finally, after all tubing is attached properly,  turn on the cold water supply. This places the filter in operation. The efficiency is determined by the temperature of the water and the pressure of the supply water. Cold water only should be used on the filter.

Because the reverse osmosis filter is rated in output gallons per day (24 hour period) , water does not pour out of the filter. The ro water is produced in a slow, steady dripping stream. Pressure is usually not a problem on city water supplies. ro membranes require a minimum of 60 pounds of supply water pressure to operate at rated efficiency. On well systems there is a simple device to boost pressure on the filter. There are many ways to install your unit. It easily fits under the sink when used as a drinking water filter. The supply of tap water can be fed with a self piercing saddle valve or a valve that goes in line on the existing cold water shut off valve valve for the faucet. A saddle valve is also available for the drain line. The product tubing can run up or down, quite a distance to any location. When the auto shut off valve senses a demand it places the ro filter in use. When the float closes the water flow, the shut off valve turns off the filter.

No. Auto shut off valves are always on complete drinking water systems. They are not a component found on most ro filters but are sold as accessories. Many hobbyist order ro filter units from mail order companies that refer them to the manufacturer for the add on options. Installing the auto shut off valve on the ro filter involves cutting all tubing and installing the valve in a precise configuration. Any time ro water is stored in a barrel, these components are necessary. For this reason, we offer a line of ro filters with these features preinstalled. For details on the barrel storage kit:

RO Filter Sales
 

Yes. When the ro filter is used strictly for drinking water a light demand is placed on the membrane. For instance a 50 GPD membrane will easily keep a standard 3 to 5 gallon drinking water storage tank topped off as water is used. However, when the ro filter is used for other applications and larger storage barrels are filled and frequently depleted of water, the membrane is placed under a heavy demand. In this case it is advisable to back flush the ro membrane on a regular basis. This simply involves opening a valve for 3 to 5 minutes to flush accumulated mineral deposits off of the membrane. Remember, water is pressed against the ro membrane and pure water passes through while solids (minerals) are eliminated by the brine reject line. With time, suspended and precipitated solids accumulate on the membrane. This reduces membrane efficiency. Back flushing removes much of this deposit. This will ensure optimum life for your membrane. Osmotic ro filters have this feature as standard equipment. Most ro filters sell this as an add on option. To add a membrane back flush valve to your existing ro filter for $15. :