Simple basic question from a new brewer.

What determines when I should move from primary fermentation in my 7 gal bucket to carboy secondary fermentation?

My instructions ( Sierra pale ale ) say 5-7 days in primary but another source says they wait 9-14 days.

I'm not even sure why i have to move to a secondary fermentation container?
Is that just to free up the bucket to brew another batch or what.
Transferring the wort is all I am doing when I go to secondary Fermentation?

Thanks for the help.

If you're going to transfer out of the primary, it's best done based on hydrometer reading, not number of days of fermentation.  Two successive days with the same reading shows fermentation is done. 

Much of current home-brewing best practice thinking says that leaving the batch in the primary for 3 or 4 weeks or even longer is not only fine, it's preferable.  The yeast has a chance to clean up after itself and you are left with better beer overall.  Fermenting sugars into alcohol isn't the only thing the yeast do and letting them have the extra days to do their whole act is a good idea. 

The main benefit is increased clarity.  Something about the transfer off 99% of the yeast helps the rest to fall out.  Not necessary, but it does help clarity from my experience.

I think all beers would benefit from extra days in the primary.  Beginners esp. follow printed recipes that say wait XX days and transfer.  I would add to R-SF's post and say that no change in the SG indicates that active ferm is ended, but that may be when the clean up really starts.  For all the weekenders out there, I would recommend you go two weeks on a few batches and see if you notice a difference.  OR, three weeks and no secondary. 

buying another bucket and brewing another batch is smart brewing too. ;D

Yah that's about right 5 - 7 days.  
Or you could go away on vacation and  rack it to the secondary when you get home.
Or you could use a hydrometer ( a total waste of effort if you ask me)  and do it by the numbers.
I own two hydrometers. One a cute little one from some brew shop supply and the other a Fisher  Laboratory instrument grade model with a real mercury thermometer built in.  I don't use either.   There is no need.

I know when I have ferment, I know when my wort is sweet,  I know when the starch is converted. I can stick my finger in the wort and taste it and I just know. I can do an easy peasy starch test will tell me if I have starch conversion.  But I also almost never do  either unless the grand  kids are around then I have them do it for the sheer science sake of it. ( exception: Oats. Always starch test when using  oats.)

There are arguments about leaving the beer on the yeast cake which won't make any sense to you until you try it a few times.
The idea being that some  people think that the autolysis ( yeast bursting and spilling their guts into the beer) is good for flavor structure in the beer.   Maybe it is and maybe it ain't. I say it's subjective and you gotta try it (or not) to see if you like it.

I am not a fan of a lot of things people do to beer.  Example: Adjuncts.  I loath 'em.   I hate raisins and all the hoards of goofy crap that some beer makers use to perk up their brews.   I think it's all cheesy crap to cover for crappy beer like Blue Moon and  company.  I loath Three Philosophers cherry beer.  I think it sucks.  But then I've had  some of the most venerable of the Belgium abby beers and I tend to dis like them and all for the same reasons. Flavor. I just don't love what they do.

And there you have it.
In Brewing, like art,, there is a lot of subjective stuff that shouldn't mean a damn thing to you until you go brew something and try it for yourself.  Some people like raisins and orange peel  and star anise and what not in their beer I think it's just plain awful crap.

So to answer your question about when to rack it off:
Whenever you please.

have to agree with CR to a point, about 50% what he says is right, I do not put crap in my beer ether, but i fermat in and open lid, never have had any problems and the rest of us German brewers that do it the old way ether, We do not leave our beer setting on the old Yeast like a lot of you all do, that is in open fermentation a Big no no, and for me even if i did a closed fermentation i would not leave my beer setting on old yeast. You are just asking for trouble. But that's just my opinion, and what we learn here in Germany, but you know what they say about opinions!

ECarroll said:

have to agree with CR to a point, about 50% what he says is right,

Click to expand...

50%?  That's a pretty specific number.

you sure it's not like 48.9856971145899310001% or maybe 52.21478009006%?

Everything has its place....
Style dictates what goes into the beer. Adjuncts like wheat, sugar, and fruit are what makes beer infinitely more diverse. I cant make a good Belgian without sugar much less entry beers like wheat beer. For me it comes down to what is the outcome I am striving for.

Back to the OP:
Keep it simple when you are starting out. Time is your friend. If you leave your beer in the primary for more than the recommended time, you will be fine, just keep the airlock filled. There is a lot to learn when you are starting out brewing. The more you learn the more techniques you will be able to incorporate into your process. The one thing I have learned is there is no wrong way to brew beer. If your beer is good, you did it right, end of story... None of the posters are telling you the wrong information. They are conveying their experience, which is all you can ask for. Take what sounds right to you, and move on.

I will say this, Pro Brewers use a hydrometer. I'm not a Pro, but I use the same method as RandomSF.

Cheers
Preston