Looking for Recipe Feedback

[Mowi]

As I have brewed a few batches of Oktoberfest from a kit (True Brew Oktoberfest beer). I was thinking about going off on my own and trying to make an Oktoberfest without the kit. I came up with this recipe for a 5 gallon batch:

6 lb. Amber Malt extract
3 lb. Pilsen Malt Extract
8 oz. Melanoidin Grains
3 oz. Hallertauer Hops
Marzen or Munich Yeast

I am partially basing this beer off of what I could find was used in the kit and what I can find at the local home brew store. As I'm not the most experienced I was wondering what others thought about this recipe. Are there enough ingredients? I remember seeing somewhere that there should be about double the amount of ingredients in weight for the batch size you are brewing. So, if you are brewing 5 gallons you should have 10 lbs. of ingredients. Will the extracts taste well together? Should I go with completely different ingredients?

Also, how would I find out how long this would need to age? Is there a calculation or formula to use or do I just taste it periodically to see how it is going? I am curious because the past five gallons (marathon style ale) I have brewed with my own recipe have brought things to my attention that I do not understand. For example, I brewed the marathon ale clone and aged it for 3 weeks. It was good at room temperature, however, once I put the beer in the fridge it was like it turned flat. The bottles that are room temperature are really good, but if I put any of these bottles in the fridge for more than an hour or so the taste changes (gets worse) and there appears to be little carbonation, even though the hiss can be heard when uncapping the bottle. The bottles that were never in the fridge have a good amount of carbonation. I can usually figure most things out on my own, but this has me completely stumped. The only thing that I can think of is that the yeast was still working and putting it in the fridge made it dormant, but I'm not sure if this is correct.

I appreciate the feedback.

 

[Yooper]

I would suggest some brewing software, as it really helps with recipe formulation. It gives you the OG, and the percentage of each fermentable. I use Beersmith (free trial, but it costs about $20 to keep) but there are other free brewing tools out there.

I don't like amber extract- it's got crystal malt in it but I have no idea how much. I'd go with light extract or extra light, for ALL beers, and then use the specialty grains to get your the color and flavor.

Melanodin malt must be mashed, so you'll have to add base grain along with it to use it.

I'd probably go a little simpler, and keep a nice clean malt profile.

Lagers are tricky. The need to ferment at 50 degrees for about 10 days, then the temperature is raised to 65 or so for 48 hours, then the beer is racked and it's held at 34 degrees for about 6 weeks. You also need to make a HUGE yeast starter for a lager.

If you're not set up for lagering, a nice "clean" ale yeast like White Labs 001 can be used at 64 degrees and it comes out ok, or else Wyeast's pacman yeast at 60 degrees is a good choice. It's not a lager, but it's pretty good anyway.