Pool owner sometimes find that their fill water is putting iron into the pool water. Especially when the fill water is coming from a well. Iron accumulates in pool water and iron levels over 0.3 ppm can cause staining.
Visible versus Soluble Iron
Filtering visible iron does not necessarily remove iron from your pool. In fact, a normal pool filter is very likely capable of filtering out visible iron.[1]
The iron that causes most of our pool issues is iron in soluble form and passes right through mechanical filtration. Then, a combination of conditions can occur in your pool that allows that soluble iron to precipitate out onto your pool surfaces and it bonds tightly to those surfaces.........making removable quite difficult.
Filtering visible iron can be done mechanically. Soluble iron is not so easy and, generally speaking, will pass through any attempts at mechanical filtration.
Sequestrants keep iron in soluble form - preventing them from precipitating on your pool surface - but the iron is still there.
R/O treatments actually remove the soluble iron but they do so through mechanical filtration
Garden Hose Filter
Many garden hose water filters for hoses have a flow rate of 2 gpm. One member put together two Pentek 150237 #10 Big Blue Filter Housing in series with a PentekWPX5BB97P 5 micron filter followed by a Pentek WP-5BB97P 0.5 micron filter with a flow rate of 10 gpm for his fill water.[2]
They screw on the end of a garden hose before the water goes into the pool. After filling the pool the filters are removed and dried in the sun to avoid any kind of mildew growth from wetness.
