Hi All, Not much experience with Liquid yeast. I got a tube of WLP500 trying to do a Trappist. I am only doing 2.5 Gal batches. (I got small equipments) The question is, for 2.5 Gal, should I only use half a tube? or throw in the entire thing? If only half, what can I do to preserve the other half? Thanks guys.
I kind of depends on the OG of your batch. Using this calculator: http://www.mrmalty.com/calc/calc.html you should need .9 vials of yeast for a 1.050 batch, so I would probably just throw the whole thing in.
Use the Mr Malty calculator referenced above, making sure to input your OG and the production date of the yeast. (White Labs vials include a "best by" date, and the production is usually 4 months prior to that.)
I recommend you compute how many cells you need and pitch that quantity . . . not too much over and not too much under. Trappist Ales start around 1.040'ish and go north of 1.080, so generalizing can be inaccurate. If I were using liquid yeast for the first time I would go to one of the free yeast calculator sites (mrmalty, brewersfriend, yeastcalculator) and input my quantity and OG. This will tell you what you need. Then input the date of your vial and this will tell you what you have. Both brewersfriend and yeastcalcualtor have excellent starter software (stepped starters if needed), use this to get to your required quantity. In addition to increasing the number of cells, a starter also increases the health of the cells you are pitching and validates that the yeast hasn't died in transit. I've had bad yeast before, much nicer to know before brewday that your yeasties have all died due to heat, time, stress, etc. Also, if you plan to use this strain again, it's minimal effort to make an oversized starter and size the excess (in your fridge) for the next batch.
^This. Plus, go here http://byo.com/stories/item/1717-yeast-pitching-rates-advance-homebrewing and scroll down to "extreme overpitching."
