Friday, November 1, 2013

Why Doesn't My Greensand Media Last?

I have had a greensand filter for years but the greensand only lasts for a year or two before I need to replace it.  Recently I found out that my water is acidic, with a pH of about 6, and was told this was one reason my greensand media is not lasting very long.  We also have some rotten-egg odor, and the greensand filter has to use a lot of the permanganate powder in order to keep up with the odor.  What do you suggest?
Gaithersburg, MD

Hi Danny,
This is actually a common problem - iron is often found in acidic groundwater because the acid dissolves it into the water.  The water may appear clear but will turn rusty when exposed to air.  In some cases, a water softener with fine mesh resin will remove the iron, though this water can be harmful to pipes and fixtures since it is both acidic and devoid of any buffering hardness minerals.  However, a water softener alone will not remove odor.
A more thorough approach would be to use chlorine injection followed by a contact tank, then a calcite filter to neutralize the water's pH, and finally your Greensand filter.
Neutralizer 7000-SXT Calcite 1.0 CF
Neutralizer 7000-SXT Calcite
The chlorine will kill odor-causing bacteria and bring the iron out of solution, making it into solid, filterable particles; the contact tank will provide enough time for these processes to occur.  The contact tank would then be followed by a calcite neutralizer, which uses calcite (crushed limestone) to react with the dissolved acid in the water and prevent corrosion.  This would be followed by your Greensand filter to remove the iron and manganese.  No potassium permanganate is required.
We recommend a Stenner pump and solution tank for the chlorinator, along with a Wellsafe contact tank.  Optionally, you could include a carbon backwash filter after the Greensand filter to remove any residual chlorine in your water.

See the diagram below for an idea of how these systems might be installed:
Click to enlarge
The result will be clean, fresh, odor-free, non-corrosive, iron-free water throughout your home.
We hope this helps you solve your odor and iron problems.  For more info, read our guide to treating iron and odor on our website.
You can e-mail us at or leave a comment on our Facebook page with any questions or comments you may have about water problems or water treatment systems.