I have no idea what this 24 hours thing is, it doesn't really make sense. It definitely won't be CLEAN after 24 hours but it will still work just fine. But 24 hours? Even after one single use they aren't sterile anymore, a few hours exposed to air would just dry the filter out.
I have, however, successfully cleaned MANY 0.22 micron wheels and the BEST way I have found to clean out the 0.22 micron wheels is:
1.) draw up hot water into a syringe (only liquid; no air) but don't fill the barrel, maybe use 2-4ml
2.) attach filter
3.) push the water through the filter, try to get most of it through, but it doesn't matter if you push it all through (without using TOO much pressure)
4.) then pull the plunger all the way to the back of the barrel and hold it there until liquid (which should now be the color of the unfiltered crap) starts to bubble back into the barrel from the filter
5.) unscrew the filter while holding the plunger all the way at the back of the barrel then throw away the unfiltered crap h2o solution and repeat these steps until water can flow through the filter easily again. You'll only be able to do this between 1-5 times (depending on what you were filtering) with the same filter until it just gets too clogged or breaks from excess pressure.
I hope I could help and good luck!
