[rj1027]

What level of calcium or magnesium would render a home reverse osmosis unit ineffective when pretreated with softener prior to the reverse osmosis unit?
 

[eugenedakin]

Hello,

The reverse osmosis unit is highly dependent on pre-treatment.  Over time, any reverse osmosis unit will eventually plug up due to calcium/magnesium/iron...etc...  The way to maximize the life of the membrane filters is to ensure that 1) the pretreatment salts are kept at high levels, 2) pretreatment filters are continuously cleaned/replaced, 3) ensure that signifacent volumes of 'flush water' is produced to limit calcification/deposition in the membranes.  Purchasing high quality membranes also extends the life of your system.

I hope this helps,

Eugene