Berliner Weisse Not Fermenting

I brewed a Berliner Weisse with a starting gravity of 1.040 but it wont ferment at all.
4 lbs German Pilsener
4 lbs German Wheat
.5oz Hops

Mashed the 8lbs of grain at 150 for 60mins. Cooled the wort to 120 degrees and added .5 lb acidic malt. Covered the wort in saran wrap and let sit for three days. On brew day, collected 5.25 gallons of wort and did a 20 min boil (15min hops). Starting gravity was 1.040. Pitched a packet of Bry-97 at 75 degrees. After 2 days there was zero activity so I pitched another packet at 68 degrees. The next day there was still no activity so I tried to aerate the wort a bit more by shaking the plastic bucket. Still no activity so in a last ditch attempt I tossed in some champagne yeast and some yeast nutrient. After 2 more days I still have no activity (no drop in gravity).
Any ideas?

the yeast detect your anxiety and refuse to work. true story.

I cant think of any reason why the yeast wont eat the sugar. I have done 30+ batches and never had a problem like this (it is my first Berliner Weisse though)

some yeast don't perform well in low pH environments - BRY-97 also has a reputation for long lag times so it could be a combo of both of those factors

BRY-97 is a notoriously slow starter, i just had a 30 something hour lag time on a beer but it's about done now. i'll bet it will start up since the chances that all of the yeast somehow died are slim and they are in the wort.

So you think I should just wait? It's been 5 days

I think that the Champagne yeast would be able to work in a low pH environment, so not sure if that's it. Do you trust that the thermometer being used during your mash is accurate / calibrated? If that was off by 10% (a long shot..) then you really would have mashed at 165°F. At that temperature, you might not have enough fermentable sugar to get the fermentation going.

Jipper said:

I think that the Champagne yeast would be able to work in a low pH environment, so not sure if that's it. Do you trust that the thermometer being used during your mash is accurate / calibrated? If that was off by 10% (a long shot..) then you really would have mashed at 165°F. At that temperature, you might not have enough fermentable sugar to get the fermentation going.

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Thanks for the idea but I feel like the thermometer us fairly accurate

I just tested my thermometer against two others and they are all within 4 degrees if each other

Jipper said:

I think that the Champagne yeast would be able to work in a low pH environment, so not sure if that's it. Do you trust that the thermometer being used during your mash is accurate / calibrated? If that was off by 10% (a long shot..) then you really would have mashed at 165°F. At that temperature, you might not have enough fermentable sugar to get the fermentation going.

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Is there a way to test for fermentable sugars?

BBQB said:

Is there a way to test for fermentable sugars?

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I suggest a quick ferment. Pull some wort out and put it in a flask, shake the hell out of it, pitch yeast into that, and treat it like a starter. See if you get any activity that way.