As for the effect "running out". I guess given enough time the silver could eventually leach out all the silver nitrate or w/e it is that makes the water toxic for microbes, but it would be a pretty long time. It would all still be in solution in your loop still so as long as you didn't flush your loop microbes should still find the water pretty toxic. How I personally would use these is to install one or two plugs depending on how big your loop is...most users with one CPU, one GPU, a few rads, and a small reservoir would be one plug users. Guys like DB that build machines that require two guys to lug them into the LAN are candidates for 2 plugs. I also run a few water features so I have more fluid volume than normal, so I would run 2 just because they are cheap. If you change out fluids that have been looped in for six months I would also install a new plug. If you have had the same plug installed for a year or more with the original fluid...might change the plug or just add a second plug as a booster maybe.

Another comment I hate to make. No, do NOT under any circumstances use these to keep your fish tank water clean.

Yes these will fit Monsoon Series One reservoirs and also the upcoming Series Two. Really they should fit almost any quality reservoir that has extra ports. Just make sure the plug is in good contact with the fluid and your all set. It does not have to have huge flow blasting over it all the time or anything like that--just good contact.