Lagering question...

So I have a lager kit I'm going to try. How important is it to step down by a degree or two per day? I already have an ale kegged and tapped in my keezer and don't really want to raise the temp past 40 degrees. Any thoughts?

Fairly important. You don't want to shock them by a dramatic temp decrease. They can put out unwanted esters because they are preparing for the cold.

Actually, at the homebrewing scale, it's probably not that important, but there is a potential risk with cold crashing lagers. I believe it is Briggs (Brewing Science and Practice) who states that sudden temperature drops can cause lager yeast to secrete proteolytic enzymes, thereby reducing foam/stability.

I slowly reduce temperatures per the recommendations because with a temperature regulator, why not? Plus, I only like to cold-shock yeast when I'm done with them. I still want a good amount of yeast in suspension during lagering. But plenty of homebrewers cold crash lagers for lagering and have not experienced reduced foam. So, it's up to you. And I think a degree or two (Fahrenheit) is conservative. I usually do 2 to 3 °F per day.

As long as you do a d-rest first you should be fine. I cold crash mine and I don't have any foam/stability issues.

The steping down is just to avoid doing a diacetyl rest, that's it. There is absolutely no problem in putting your ready-to-lager beer under subtle refrigeration.

I personally just do a 24 hour diacetyl rest by transfering the fermenter to room temp before lagering at 38-40F.

There is an excellent article in the homebrewing wiki that really elucidates the lagering fermentation schedule. Especially interesting is this chart, which shows that various temperature schedules can be used to good effect, depending on your priorities or capabiities:



The entire article is here: https://www.homebrewtalk.com/wiki/index.php/Fermenting_Lagers

Basically, it is considered 'best practice' to maintain fermentation temps until fermentation is nearly complete, then very slowly lower the temperature until you reach lagering temps. This makes it so the yeast doesn't go dormant; they continue working and refining the beer the entire time, even during lagering. But this level of temp control isn't practical for many homebrewers, so we often will just use a diacetyl rest near the end of fermentation, then cold crash it to lager temps. This has much the same effect.

edit: for reference, the traditional German lagering schedule is graph A. The schedule most commonly used by homebrewers who don't have strict temperature control is graph F.