Frequently Asked Questions About Greensand Iron Filtration:
(1) Q. Why are these
systems called "greensand"
A. These filters use 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.
Q. How do they work?
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.
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 double rinse makes sure the filter bed is free of any permanganate residual.
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
A. Yes! There are very specific conditions required. The water must have a pH of 6.7 to 8.8. 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 also has a very
bad smell of sulfur, is this a problem?
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.
Q. If I chlorinate 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 dosage can be drastically reduced.
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.
Q. What maintenance is required?
A. Once every one to three months, a few pounds of dry potassium permanganate powder is added to the little solution tank. The control valve injector screen should be cleaned yearly.
Q. Will there be a pressure
loss through the system?
A. Properly sized, the system produces a very low pressure drop at service flow rates, usually around 5 psi.
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.