I plan on brewing a Karmeliet (tripel) clone. I harvested the yeast from a couple of bottles and attempted to bring them back to life. The process was so slow that I gave up and smacked/started some commercial yeast (Wyeast 3522-Ardennes). I guess the Karmeliet just needed some competition, because it took off after seeing the Wyeast starter. Now I have a Wyeast 3522 ready to pitch, and some authentic Karmeliet yeast (quantity is low but growing). My common sense says to stick with a single proper yeast. But it is tempting to add the two together. The White Labs website says "yeast can live happily together". They have no reservations on mixing yeast strains at the beginning of fermentation. The styles of the two strains are similar and fermentation temps are compatible. Is the idea of combining the two strains brilliant or ridiculous?
I don't see why this would be a bad idea. If you want it to be more like Karmeliet, obviously that yeast is the way to go, but two strains might be interesting.
If you are confident in your sanitation, give it a try. Bear in mind that the outcome is probably dependent on the initial pitching rates, the fermentation temps, the wort, etc. I've blended yeast before for various reasons and (lack of reason), and never had a beer experience. I'm not sure I discovered anything unique, but I never did anything like a controlled experiment, either.
One thing to keep in mind with the clone is that the bottling yeast may not be the same as the yeast strain used for fermentation. Bosteels ferments TK, then lagers it for 4 weeks, before filtration to remove yeast and haze. It then re-yeasts and bottle conditions with sugar. You may want to shoot them an email to see if it is a different strain used for bottling (e.g. champagne yeast, etc.).
Sounds like you're in a perfect spot for some experimentation. You could brew it and pitch the 3522 while building up more of the Karmeliet yeast. Brew the same recipe again and pitch all the Karmeliet yeast into it. Then you'd have the same beer with different yeasts side by side for comparison, while also having a fresh cake of each yeast that you can play with and mix together in a third beer.
Thanks for everyone's words of encouragement. At the last minute I lost my nerve and pitched the 3522 only. I had heard second-hand that Karmeliet bottle yeast is the real thing, but the Brewers van Bosteels choose not to enlighten me. Results are as expected from a fresh commercial yeast that was properly started, I attached the blow-off tube this morning. The Karmeliet yeast is saved and will consider experimenting with it in the future.
I say you'll be ok. A brewed a Tripel last summer with two different Belgian yeasts from White Labs and the brew came out just fine.
