So, I had set up a RCS tank for my girlfriend about 2 or so years back. I used roughly 3 gallon critter keeper. It worked well. A few months later we decided to rescue a few bettas from Wal-mart and needed tanks to put them in. We put a nice yellow crowntail in with her shrimpies figuring he was a toss up whether he would go after them or not, and there were quite a few hiding places they could get to that he couldn't if needed.
We had him a good year and a half before he finally passed. Pretty good considering who knows how long he was at Wally world. We hadn't seen any shrimp in the tank for the past 6-8 months and figured he had taken them all out.
It was time to break the tank down for now until I could figure something else to do. After removing all the rocks, wood and plants, I started pouring the water down the bathtub drain. Then, I started seeing streams of clean under the muck. Sure enough there were surviving shrimps.
I quickly covered the drain so none would get flushed (hopefully none got past me) and got a bowl to put whatever I was able to save into it.
The critter keeper was in no shape to set back up for either a temporary quarantine or permanent home at this point, but being a hobbyist like all of you, I had an empty 2.5 gallon, 5.5 gallon and 10 gallon tanks waiting for an idea.
I grabbed my 2.5 gallon, filled it with treated water that I keep on hand for water changes, threw some anubias nana from another tank in it, and a couple of moss balls, and transferred them to their hospital tank.
I plan on keeping them in there for 2 weeks to a month to keep an eye on them, make sure they survive. Then I'll set up something more permanent for them with some good substrate and then purchase some new shrimp to introduce some diversity into the gene pool as these guys are several, SEVERAL generations in from the same stock, and have lost some of their initial vividness.
(Edit: This should have actually be posted in the Invertebrates forum, sorry, my bad.)