Comments/questions inline:
-I feel my temps were off during the mash process....
Did you measure your temps? If so, what were the specifically, or at least in what range?
-I usually do closed fermentation, but THIS TIME decided to use my plastic open fermentation
How open? Like top of the bucket left off for a day, two? A week? Or was the lid just resting on top of the bucket, but not sealed down?
-Being my first mash, I noticed I was not as a efficient I guess at my mash since my OG was below what was calculated using Beertools
What efficiency were you assuming?
-Once I noticed the krausen was down, I put it into a secondary fermenter for about 2 weeks.
So you moved it as soon as the krausen dropped, did you take any gravity readings before moving it?
Without having the answers to my above questions, I'll provide some info based on assumptions which I can correct later if the info you provide is different enough to warrant it.
1. If you don't know what your temps were in the mash stage, this is your first problem. A couple of degrees Fahrenheit can make a big difference in the fermentability of your wort, and this also ties directly in to your efficiency.
2. With regards to open fermentation, if you truly just left the lid off without even mutting as much as a cheese cloth over the top of the bucket, you're just asking for an infection. Flies, dust getting blown out from an AC vent, someone sneezing in the vicinity of the beer, and a myriad of other things are just waiting to get into your beer to contaminate it. Sure, you can do open fermentation successfully as a home brewer, but certain precautions must be taken still.
3. Moving a beer before it's done fermenting in the primary can cause a stalled fermentation, which can lead to vast quantities of diacetyl in your beer*. If the beer is within a couple of gravity points of finishing, you can usually move it without problems, say if you wanted to use the last few gravity points to naturally carb the beer in a keg or cask, but moving after the krausen drops doesn't tell you anything about the state of the beer. Sure the most active part of fermentation is over, but you could still have 10+ gravity points to drop. It is very important to use your hydrometer before doing anything with your beer post fermentation.
*Diacetyl is a an intermediate product produced by the yeast during fermentation. Some of it hangs around for a while, but eventually the yeast come across it and it gets reincorporated into the fermentation process and converted down to the appropriate fermentation by products (ethanol and CO2). If the yeast aren't given the time to finish their job, they won't go back and find all the excess by-products they created and clean them up, which gives icky off flavours.
