I respectfully disagree. Iron will settle out as it has a higher specific gravity than water. My guess is you may be dealing with very small clay particles (colloidal clay that is negatively charged) that are natural in your area that won't settle out. In the state of Oklahoma there is an area where all the bodies of water will not settle out and stay reddish brown indefinitely. It's due to the soil in the region.
I would try something to bind the particles and cause them to settle if this truly is not a form of planktonic algae or animals stirring up the bottom.
Have you tried adding a small amount of alum you can get at the grocery store to the jar? Bill Cody can tell you if you're dealing with planktonic algae if you send him a fixed sample.
Last edited by Cecil Baird1; 11/21/14 03:36 PM.
