Keg Fermenting

I would like some advice as I plan on soon starting to ferment in kegs. Could anyone offer me advice or tips to doing it? Or maybe even advice on a setup for this. I would kinda of like to do this with as little as equipment as possible, i mostly decided to do this because of wanting to brew a lager and this was my only option at fermentation of a lager.

 

Fermenting in a corny or or a Sanke keg? Makes a big difference ;-)

I ferment in a Sanke using this:
http://www.brewershardware.com/American-Sanke-Keg-Fermenter-Kit-with-Thermowell.html

Love this setup

 

I was planning on using a corny keg might help specifying.

 

I am fermenting in closed kegs under pressure so the beer also carbonates with produced CO2.
You just need spunding valve with pressure gauge, this is my set up with non-adjustable safety valve:



I keep open valve for 1st 3 days and then close it so the pressure can build up.

More about it:
http://www.homebrewtalk.com/wiki/index.php/Closed-system_pressurized_fermentation

http://www.homebrewtalk.com/f13/closed-system-pressurized-fermentation-technique-44344/

 

How do you ferment 5 gallons of beer in a 5 gallon keg without losing a bunch to blowoff and generating a ton of trub in the bottom of the keg???

For lagers, I primary in buckets, and then transfer to kegs, and Lager in the kegs and force carbonate.

I guess that is my big question..... don't you end up with 4 gallons of beer?

 

No-one says that I ferment 5 gallons, they are filled with 4.5 gal and depending on yeast there is more or less amount of yeast in blowoff but usually not significant since there is half gallon of head space, with adjustable spunding valve there is less yeast on top since pressurized fermentation decreases head.
With some strains like hefe I add 3rd keg which acts like airlock, it is filled with 1 cup of starsan and prevents air income.

As for final volume, yes I end up with ~4 gallons of beer in each keg.

 

A question regarding this would I need to allow extra room for blow off if I only did lagers in this method?