Adding more yeast?

I was attempting to make a marzen beer that was supposed to be fermented for six weeks but at the brew store I was given a Munich Wheat yeast pack. I used it and the fermenting has seized within a short amount of time. This is really not what I wanted. Could I possibly rack into another fermenter and pitch some ale yeast instead and age it as would? What would happen?

Oh dear....did your LBS guy accidentally grab the wrong yeast for you? Marzens are definitley lagers. You should list your recipe and then we can see what kind of beer you might have now! Probably a dark, caramelly, cloudy beer.

If the active fermentation is over, pitching another yeast isn't going to do anything. You won't get the characteristics of the yeast unless they are involved in the active fermentation.

At this point, you'll just need to finish this one out. You CAN, however, still get a good bit of the lagered character following the lagering technique for this ale yeast.

The main characteristics of a good Marzen is the chewy caramel malt backbone coupled with the crispness of lagering. You'll still have your malt backbone. Lager the beer at about 30F for 6-8 weeks, and you'll get most of the lagered crispness.

You're just additionally going to have some of that clove/banana wheat yeast character, but with the strong Marzen malt character, it should be minimally noticable.

Lager this beer, and you'll get most of the way to a to-style Marzen.

Good luck.

That's 2 degrees below the freezing point of WATER, not beer.

Beer at 5.0 ABV freezes at 28F at sea level. More ABV = lower freezing temp.

30F is optimum lagering temp if you have enough control to hold it there. Otherwise, build in your temp contoller's differential.

The colder you can get it without freezing, the better, as the lagering weighs down and pulls out finer and finer protein particulates.

I keep my controller's differential at - 3F, so I personally lager at 33F. If I tighten the differential any more than that, the compressor cycles too much. It cycles about every 35 minutes or so with that differential, which is good for me!

The recipe I was going from was called an Oktoberfest or Marzen Ale. The recipe went

3.3 Lb Amber LME
3.3 Lb Light LME
0.5 Crystal 80L
0.5 lb Munich
0.5 Pale Malt
0.25 Chocolate malt
1 oz Hallertau
1 oz Hallertau
One thing I don't believe I mentioned was that I wanted to make a Pumpkintober type beer so I added roughly three pounds of roasted pumpkin to the boil as well.
and the yeast was supposed to be German Alt but he ended up giving me Munich Wheat Yeast.

So what kind of beer is it now? It can't be a wheat beer right? There is no wheat in it. Just wheat yeast...

The main characteristic of wheat yeast is it is going to have low flocculance, i.e., it tends to stay in suspension and is tough to clear.

In a wheat, of course, you want yeast in suspension in the final beer, as that yeast adds to the proper taste of the wheat.

In a Pumktoberfest, not so much.

A good way to combat this would be to go buy a pack of unflavored gelatin. Add about 1/2 of that pack of unflavored gelatin about 12 hours before you rack over to bottle/keg, and it'll coagulate most of the yeast in suspension and clear the beer so it's back to more like a baseline ale.