First Lager - Two Questions

So I am doing my first AG and doing a Pilsener Urquell clone. I have everything I need - extra fridge, SS fermenter with trub dump valve, and Yeast Starter set.

That being said, I haven't done any of this yet. I have never made a yeast starter and bought a 2L flask. Brewers Friend tells me I need to do at least 5L. So strike one for me. Any suggestions? Also, I bought a stir plate but it doesn't tell me how long to leave the stir plate on for to complete the process.

Second, I have never needed to use a blow off tube and now will need to run the line outside of a fridge. How do I keep the fridge door closed? I don't really want to drill on a lock or anything.

Thanks.

Try http://yeastcalc.com/ and see if you can get the number of cells you need in two steps. You will need another day or two to prepare the starter. I let my starters sit on the stir plate for 12-24 hours, then cold crash.

Cool, thanks. This seems to have computed my needs a better rate than Brewers Friend. This is the result, tell me what you think:

Lager, 5.25g batch, 1.054 OG, O.P.R 19.9m per ml, 397B cells
1st Step: Starter Volume 2L, Inoc Rate 48.5M, New Cells Created 213B, Total Cells at Finish 310B

I don't understand the DME calculator cause it is telling me 1.037 OG, 1.5L Starter and DME to add 5.2 ounces.

Please connect the dots for me. Thank you.

The DME calculator is just telling you how much DME to use to make a starter wort at whatever OG you ask for. You have to plug in your own numbers (OG and starter volume), it's not reacting to the rest of the calculator. The OG is up to you, but something around 1.040 is standard. You certainly don't want to go much higher than that.

You may want to try bumping up to a 2.5L starter to see what the numbers are. 310B is about 25% less than the optimal rate it gave you, Probably not a big deal, but I opted to be conservative in case my starter was less effective than predicted. Everything I've read says that, especially for a lager, a slight overpitch is preferable to a slight underpitch.

Regarding a blowoff tube, I always just keep the blowoff jar inside the fridge. If you need to come out, there's no choice but to cut a hole somewhere.

Read about Narziss fermentation for lagers.

You probably wont need a blow off, lagers are less vigorous than ales.

Zeg, under those conditions I don't have a big enough flask to support that much yeast. So I bought the 2L flask thinking it was big and essentially it is too small for anything shy of ales ... and I only do 5g batches. So for 20 gallon batches I would need a gallon of yeast???

Bear in mind that I have limited experience with this, so what I'm saying is mostly based on reading and playing with the calculators.

For a big batch, yes, you will need a lot of yeast.

You can pitch more than one vial of yeast into a starter to get more cells out of a smaller volume. At least, that's what the calculators say. So that's a possibility.

You can also do a multi-step starter in your 2L flask, decanting between stages and pouring in fresh wort. I don't know how to calculate this exactly, but I'd guess that you would use the number of cells predicted for the output of your first 2L starter as an input to a second 2L starter.

I recently made a 3L starter with 2 vials of WLP833. I don't have a flask at all, I just used a glass 1-gallon cider jug that I saved from a while back. If you're going to use a stir plate, this won't work, but it's an option.

EDIT:

I just had a look at yeastcalc and found that it can do this for you. Just enter a second stage. For your case, assuming a stir plate, 1 vial of yeast at 75% viability (about a month old), and two stages of 1.5L starters, you will end up with 442 billion cells. That's probably your best option. If you don't have a stir plate, though, you'll either need larger starters, an extra stage, or a second vial pitched in your first starter.

Indeed, a 2L flask isn't quite enough for many lagers. I often do a 2-stage starter with the 2L as stage 1, then move to a 4L growler ($5 from any LHBS) for stage 2. You can indeed use a growler on a stir plate, but it's a little noisy or wonky depending on how flat your bottom is. I can't get mine to spin fast enough to aerate it (like I can do in a flask) without throwing the stir bar. But it works fine, I just have to use the aeration stone for a few minutes at the start. (in a flask, I spin full speed for 10 minutes to aerate.)