RODI micron question

[Myka]

I was just digging up some links for another thread, and came across Randy Holmes-Farley's comments on what passes through RO membranes:

"However, at the small end of the spectrum a number of compounds can pass through a reverse osmosis membrane to some extent and are, therefore, of concern to reef aquarists. These include carbon dioxide (CO2), ammonia (NH3), hydrogen sulfide (H2S, especially a concern with well water) and silicic acid (Si(OH)4, which is the uncharged and predominate form of silicate at pH values below 9.5). All of these should be trapped by a functioning DI resin (discussed below), but can still be a concern."

Obviously, there isn't a 100% fail rate with these compounds either though.