co2 pressures and cornelius kegs?

I am going to put my first batch in a 3 gal cornelius keg, and also bottle the rest but, do I need to use a priming sugar when using the keg with co2? And how much co2 for a 3 gal keg versus a 5? Also I am finish up the other keg right now, a 3 gal batch of Sam Adams clone, a friend told me to store the beer after a pull at 20lbs is this right? Then when I take a pull (fill a glass) I should knock down the relief valve till around 5lbs so I can get some beer instead of foam. So my ?'s are

1. After racking into the 3 gal keg sugar or not?

2. What pressure do I need on the keg after racking?

3. What is a good serving pressure (setting the reg @ during drinking)?

Thanks

If your using co2 you don't need priming sugar.
A 3 gallon cornie will carb pretty fast, I don't go with high (30psi) pressures to force carb like I do with a 5 gallon cornie.
I would set it at 12lbs and leave it for a week, you can pull samples and check as often as you like.

Your friend is nuts. Never turn your beer any higher than the psi you want it carbed at, after it's fully carbed.

Thanks for the info, so 12lbs is what you would set it up for as well if you were to have some freinds over to drink as well?

I keep mine at 12 psi at all times. My kegerator is 40 degrees, and I have 8 foot lines. You'll need to balance your lines. If you have short lines, if you dispense at 12 psi, you'll get a glass of foam.

There is a carbonation/line balance chart in one of the stickies in the kegging forum. I'll see if I can dig it up.

Here's the FAQ. This answered a lot of my questions when I was trying to set up my system!

https://www.homebrewtalk.com/f35/sticky-kegging-faqs-43347/

Mainebrew said:

Thanks for the info, so 12lbs is what you would set it up for as well if you were to have some freinds over to drink as well?

Click to expand...

It also depends on the beer style, it can vary from 8psi up to 14 to 16psi for some wheat beers. 10-12 is a good start, i have 6 foot lines an have no trouble with foam, but it will vary by setup. Set it and forget it.

Here's a chart for various styles.
Force Carbonation & Carb Table