Frequently Asked Questions About Greensand Plus Filter Systems:
Q. Why are these systems called "greensand" iron filters?
A. Originally these filters used a specially formulated filter media made from a naturally mined form of glauconite greensand. The greensand filter media has a special coating of manganese oxide, which oxidizes iron, manganese and iron in water, upon contact with the filter media. We use an improved form of the media call Greensand-Plus, which last longer and works better than the standard greensand media.
Q. How do they remove iron and manganese from water?
A. Iron and manganese are metals often found dissolved in water. They cause stains when exposed to air in the laundry, bath, etc. by oxidizing or "rusting." The greensand filter media oxidizes dissolved iron and manganese on contact, as the water flows through the greensand filter, and causes these elements to precipitate (or form solids) in the bed of the filter. The iron filter backwashes these small particles to drain every few days in the middle of the night (or some other preset time), thereby cleaning and restoring the filter media. To provide the oxidizing power to precipitate these metals, the filter is automatically cleaned and restored with potassium permanganate (a purple liquid) during each backwash cycle. If potassium permanganate powder is not used, then a chlorine injector pump is used ahead of the greensand-plus filter to regenerate the filter media.
Q. Someone told me greensand iron filters are "old technology" or obsolete, is this true?
A. No. Greensand iron filters are a proven technology that has stood the test of time. If your water has high levels or iron, manganese and/or sulfur odor, it can be an excellent low cost iron filter. As long as you are willing to add the potassium permanganate to the solution tank several times a year, and follow our simple maintenance procedures, the iron filters will last for years and produce great water.
Q. Is potassium permanganate toxic or harmful?
A. Potassium permanganate is a powerful oxidizer and, similar to chlorine, can cause skin irritation or burns if direct contact were to occur. But, no permanganate is added to the filtered water. The permanganate is only used to backwash and clean the greensand filter media. A special rinse cycle makes sure the filter bed is free of any permanganate residual.
Q. What is the difference between "greensand filters" and "greensand-plus filters"?
A. The difference between GreensandPlus and manganese greensand is in the substrate that forms the core of the media and the method by which the manganese dioxide coating is attached to that substrate. GreensandPlus has a silica sand core and the coating is fused to it while Manganese Greensand has a glauconite core and the coating is ionically bound to it. The silica sand core of GreensandPlus allows it to better withstand operating conditions in waters that are low in silica, TDS and hardness. Due to the improved performance of Greensand-Plus over regular manganese greensand, we now use only Greensand-Plus for all our greensand appliacations. It is an exact replacement for standard greensand and can be either regenerated on an intermittent basis by using potassium permanganate powder, or by using a chlorine (or hydrogen peroxide, or ozone) feed ahead of the greensand filter.
Q. What is the difference between "greensand iron filters" and Catalox iron filters?
A. The difference between Greensand iron filters and Catalox filters is the type of media used. Catalox filters use Catalox (similar to Filox and Pyrolox meda). Greensand is a lighter media, created by coating silica with a manganese oxide coating. It needs to be regenerated with potassium permanganate, or use with chlorinated water, where chlorine bleach is fed in upstream of the filter. Catalox is actually pure manganese oxide, it is not a coating. It is much heavier, requires a much higher backwash flow rate. Catalox can work in some applications where the iron levels are less than 5.0 ppm and there is no sulfur odor present and last for years with just simple backwashing. In these applications, no chlorine feed is required. However for many waters with hydrogen suflide present, or higher levels of iron, and/or manganese, a chlorine feed is recommended ahead of the Catalox filter. To ensure longer life, we do recommend a chlorine feed ahead of the Catalox filter.
Q. Do these systems come in different sizes?
A. Yes. The size of the system is directly proportional to the flow rate of the water, in gallons per minute. The higher the flow, the larger the system required. Recommended backwash flow rates must be observed.
Q. Do these filters have any special conditions in order to work properly?
A. Yes! There are very specific conditions required. The water must have a pH of 6.7 to 8.8. If the water has a pH of less than 6.8 we usually recommend treating the water first with a neutralizer filter or a soda ash feeder. The best applications have feed or raw water of less than 15 PPM of iron and manganese, combined. The maximum practical removal rate for hydrogen sulfide is 5 PPM. The water should contain no tannins or oil.
Q. My water has a very bad smell of sulfur, will this be removed?
A. While these greensand filters will remove up to 5 PPM of hydrogen sulfide, in some cases the odor can be coming from conditions that exist after the water enters the plumbing. For instance, water heaters often have decaying anode rods that create hydrogen sulfide gas, so that even if the water entering the water heater is clean and odor-free, you can still have an odor problem. It is important to identify the source of the odor and to verify that it is in the cold water also, which would indicate that all the incoming water has an odor. In many cases, a thorough sanitizing of the household plumbing with chlorine is recommended after installation. Also see our report on How To Treat Odors in Well Water.
Q. If I want to use a chlorinator for my water, can I use this type of iron filter?
A. Yes. These iron filters actually work better with a chlorine feed. They also work great after the water has been ozonated. With ozone or chlorine pretreatment, the permanganate can be eliminated. If the water is extremely high in iron (over 10 ppm) then both a chlorine feed and the permanganate powder may produce best results.
Q. I have very high manganese (greater than .05 PPM), will these iron filters remove manganese also?
A. Yes, these systems work great to remove manganese, both dissolved and oxidized. For manganese removal these are an excellent option, as many iron filters do a good job of removing iron, but do not do a good job at removing manganese.
Q. What maintenance is required?
A. Once every one to three months depending on how often the iron filter is set to backwash, a few pounds of dry potassium permanganate powder is added to the little solution tank. Once a year there is some general maintenance that should be done to the iron filter and permanganate solution tank, which takes about one hour. No special tools are required.
Q. Will there be a pressure drop through the system?
A. Properly sized, the system produces a very low pressure drop at service flow rates, usually around 5 psi. Most people don't see any pressure loss in their household piping.
Q. How much backwash water is required for the greensand filter?
A. Typically about 60 to 100 gallons depending on the tank size and settings or the equivalent of about 3 extra showers or baths per week.
Q. I understand the greensand filter backwashes automatically, but how often does it need to backwash?
A. Most greensand fitlers are set to backwash once per week, but if the iron is over 5.0 ppm and a lot of water is used, it might need to be set to backwash every 3 to 5 days.
Q. Can I route the backwash water to my septic tank?
A. Yes. The backwash water can be routed to the septic tank with no problem in almost all cases.
Q. How frequently do I have to replace the filter media?
A. The filter media will last for 4 to 8 years depending on usage and conditions. It is easily replaced. Need more information?
Q. Do the greensand iron filters need a whole house cartridge-type filter installed either before or after the system?
A. If the well water contains any grit or sand, a flushable filter strainer is recommended before the greensand filter. Generally, we do not recommend installing a 50 micron or smaller filter before the greensand filter, because it can become plugged up with rust and prevent the greensand filter from backwashing and regenerating correctly. Some customers do install a 50 micron filter after the greensand filter, in order to finely filter the water. This type of whole-house filter also makes it easy to shock chlorinate your household piping, by just adding a 1/2 cup of bleach to the filter housing and turning the water back on, and flushing chlorinated water into the water and house hold pipes.
Q. Can I get assistance in choosing an iron filter system for my application?
A. Yes! You should first have your water tested, and then contact our technical staff for help on selecting the best iron filter system for your application. Also see our Custom Water System Design Questionnaire which makes it easy to help you select a system.