All the new Monsoon fittings, and even new versions of their previous fittings, now have barbs or bases made with antimicrobial silver.
There's been some thought for some time that silver does not play well with nickel. EK used to frown on silver used with any of their nickel blocks (though they have since abandoned that stance), and Koolance still says any silver with any of their nickel products voids the warranty on them. That, and Martin generally discourages the use of silver with nickel, especially if they come into direct contact, which would be the case if a monsoon fitting was screwed into a nickel block.
Personally, I just prefer to run distilled plus Nuke in my loop, and just don't really want to add silver which just further increases the galvanic potential in a loop that otherwise is mostly copper, nickel, and brass.
Edited by Unicr0nhunter - 4/3/14 at 8:16am