what do you guys recommend for the size. I was thinking 5 micron. Just the one filter more than likely and add another if I felt that I needed to filter it out more.
5 micron is usually sufficient to polish. Don't bottle condition, though, or you'll end up where you started, as far as turbidity goes.
Do you rack to a keg pressurize then immediatley push through a filter to a second keg?
Got it in one.
Can you do the same with Cider for clarity improvement?
And wine, and tea, and and and. Filtration removes solids which adversely impact clarity (turbidity). It really doesn't matter what you're pushing through the filter, as long as it's liquid and you want it to be bright/shelf stable.
Filtration is something homebrewers can safely ignore, because it's true that patience is a virtue, but it's unwise to completely poo-poo it, as some do. It doesn't strip flavor, not that I've ever been able to notice, but then my experience wasn't blind sampling (anyone know of a blind tasting experiment?). If you
do notice flavor stripping, factor that in your recipe design. Simple.
Things to keep in mind:
1. Chill your green beer. Chilling precipitates yeast.
2. Fine your green beer. Fining precipitates damn near everything, depending on your choice of fining agent.
3. Force-carbonate the result. The main reason you want to filter is for bright beer. If you filter, then bottle-condition, all you're doing is building the yeast colony back to visible turbidity! Self-defeating.
3a. It's easier to carbonate cold beer in the keg.
Cheers!
Bob (who filters All. The. Time.)