No vendetta, just pointing out the obvious.

Like I said, if you want to discuss RO, start a new thread. I cant move it or start a new one since I dont have the ability. Maybe a mod should move the RO discussion to it's own thread and close this one out.

No problem, if this starts to grow legs I will post a new thread, just a few questions for now though.

Dissolved chemicals, such as CYA and calcium and carbonate ions, etc. have molecular sizes on the order of from 1 to 10 Angstroms. Even a 0.5 micron filter is 5000 Angstroms because 1 Angstrom is 0.1 nanometers. There are 10,000 microns in an Angstrom. Even a long-chain polymer like PolyQuat is on the order of 3000-5000 daltons (g/mole) molecular weight with a polymer structure shown here implying 12 to 20 units in the polymer so is maybe 250 Angstroms (0.025 microns) long and therefore would not get caught in an uncharged filter (however, PolyQuat is positively charged so would bind to a cationic exchange resin, for example).

Reverse osmosis uses specialized membranes with extremely small pore sizes. It's quite different than regular filtration, requires substantial pressures, and is slow to filter unless membrane filter areas are extraordinarily large.

Phosphates by themselves are ions in water so would not be removed by normal filtration, but would by RO. However, phosphates precipitated by adding lanthanum to form lanthanum phosphate can be readily filtered out as it forms precipitated solid particles (crystals). The water may remain milky for some time if a clarifier is not used as the precipitate is otherwise slow to consolidate.

Thanks Richard, I found a chart earlier that helped with the size of various contaminants.