So I recently posted this picture of a split batch tripel using wlp 500 and wlp 530. The recipe is a 1.083 OG all pilsner with 2.5 lbs of cane sugar for 6 gallons at the end of the boil. The wort was cooled to 64 pitched and each carboy was aerated with 1.5 liters of O2 for 90 seconds measured with a flow meter. Yeast starters were made side by side and production date of the yeast vials was within a week of each other. Fermentation started at about 13 hours and was vigourous - see the picture, both were jumping out of the fermenter. Fermented at 64 and slowly raised to 70 over the first few days.
So here is where we are right now - the WLP 500 is at 1.012 and and the WLP 530 is at 1.036 - neither is currently showing signs of active fermentation.
I have made this recipe with WLP 500 3 times in the past and have won awards with the beer, tastes great in the fermenter right now. This WLP 530 is a mystery to me, never used it for this recipe before. I am wondering if this could be a case of that yeast not playing well with the cane sugar addition in the boil - all those simple sugars up front got gobbled up and the yeast tired out before attacking the maltose. However the WLP 500 just blasted through it (which is consistent with my prior experience).
Now I want to go back and rebrew this beer but add the sugar at mid fermentation and see if the results change.
In the short term I am going to jack up the temp on the 530 to 74 degrees to see if it will get rolling again. If that doesn't work I will rack the WLP 500 into a corny and create a starter out of the yeast cake to pitch back into the wlp 530 stalled fermentaion once super active.