Advice on next step, big beer fermentation

[MillriftJim]

A few weeks ago I did a parti-gyle brew, with two separate runnings from the mash tun. The first running is a strong porter, the second a weaker session porter. My question is about the strong beer.

Ok, so the OG in the strong beer was about 1.094. I took about 1.5 liters of the wort and set aside in a sanitized jar, and pitched a 1.5 liter starter wlp320 (American Hefe), this was a flavoring decision. At high krausen, I began a starter with the wort I had set aside, using wlp001 (California Ale). After about 24 hours, I pitched this starter into the fermenter (the starter looked good). At this point, gravity of the beer was down to about 1.050 or so, and there was a vigorous fermentation. The vigorous fermentation continued for about 24 hours or so, and then largely subsided (meaning there was not much visible activity).

Earlier this week, I took a gravity reading at 1.036. Two days later the gravity was still at 1.036. At that point, I gave the fermenter a bit of a shake (5 gallons, btw), and raised the temperature a few degrees from 68 to 72. I'm going to wait a day or two to take another reading and hope that the gravity has inched down a bit, if it has I'll probably just shake up the fermenter again and wait another several days or a week. If it hasn't, I'd like some advice on what to do next; I'd like to get the gravity down to about 1.022, which as near as I understand would be about 75% attenuation.

As I see it, I could prepare and pitch another starter, probably of wlp001 (ABV is currently about 7.6%) or maybe some dry yeast I have (pack of Nottingham?). There is also the other beer, the small beer from the same mash. This started out at 1.036, and had a wlp001 pitched into it. I haven't checked the gravity of it yet, it doesn't look like it's done fermenting yet (It seems a bit slow, but it's progressing and I'm not worried). I could rack my bigger beer onto this cake when I keg the smaller beer...is that a bad idea?

Ok, sorry for long post, and thanks for reading and for any suggestions offered!

 

[Biobrewer]

So you brewed the 1.094 beer. You pitched a 1.5 L starter of WLP320. This was probably a big underpitch. Since you gave little info about the starter, I'm assuming that you do not use a stir plate. If that is true, you would need 318 billion cells for 5 gallons at 1.094, which you would get pitching a brand new vial into 5.3 L starter. You pitched a vial into 1.5 L, giving you 178 billion cells. SO, right there, your yeast was probably massively stressed upon pitch.

Then, you made another starter using WLP001 and pitching that into 1.5 L of wort (1.094 OG) that you set aside. Here, I see another major problem, that being you used 1.094 wort for a starter. You should typically keep the OG of the starter around 1.04 for good growth and less stress to the cells. Pitching into 1.094 wort did not do the yeast any favors.

Also, with big beers like this, I have noticed that in order to achieve maximum attenuation, I NEED to aerate my wort with pure oxygen. It is one thing I started doing that resulted in noticeably better big beers with good attenuation.

All around, your wort was probably under-oxygenated, and the cells you pitched both times were either inadequate (first pitch) or inadequate and highly stressed (second pitch).

You can try putting it on a cake to see what happens. Not sure you'll get much more out of the cells you already pitched if they are in bad shape.

Good luck!