Originally Posted by keystoner
i am about to make my first yeast starter. i ordered the 1000 ml flask from northern brewer and it just arrived. however, it says that the instructions are for making a starter using a wyeast activator pack but my ingredient kit came with safale us-05. can i still use it? also, when you pitch the yeast into the starter do you use all of the yeast? how long do you usually let the starter ferment?
You normally only want to make a starter for liquid yeast. The reason is that quality dry yeast (like S05) are packaged so that there are enough cells to ferment almost any 5 gallon batch, plus they have certain reserves due to the way they are packaged. The manufacturer does suggest rehydrating, though.
Here's a blurb from Jamil Zainasheff on dry yeast and starters: "Another case where you generally don't want to make a starter is with dry yeast. It is usually cheaper and easier to just buy more dry yeast than it would be to make a starter large enough for most dry yeast packs. Many experts suggest that placing dry yeasts in a starter would just deplete the reserves that the yeast manufacturer worked so hard to build into their product. For dry yeasts, just do a proper rehydration in tap water, do not make a starter."
For liquid yeast, you almost always want to do a starter.
Great info from mrmalty.com on starters here: http://www.mrmalty.com/starter_faq.php