We seem to have some kind of metallic or strange taste in our last few beers. Strangely enough, the taste only seems to come through with lighter beers such as pale ales or IPA. Our other darker beers such as a stout, irish red, and porters don't have this taste. I'd imagine that the taste is there still, but the darker and more rich flavors have masked it out.
I've narrowed it down to a few issues which may be the cause of our problems
1. Thermometer mismatch - I've found our thermometer to be off by quite a far range. We have since purchased two different types that are within each others mark by 1-3 degrees. I work in a test lab and plan to bring them in and see how well they operate in calibrated environmental chambers for another check.
2. Grain in mash coming into the boil pot. We can flush multiple gallons back into the mash but we never seem to be able to get all the grain. Even though they are pretty small specks of grain that get into the boil, I can't imagine this being a good thing with releasing Tannins.
3. Water supply. I have attached a copy of our latest water report that may have something to do with it. We have not been using any additives and in the past had not had any problems. I'm just aware that different styles of beer call for different types of additives.
4. Improper cleaning. This one seems far fetched to me considering that it would be pretty improbable that the lighter beers were not cleaned right while the darker ones just so happened to have been. I've found through research that others don't have a problems fermenting in 1/2 barrel kegs and I clean our plate chiller with sterile water and baking in the oven.
I just ran downstairs and tasted out latest two batches. These have been carbonating in the keg for a week and are not quite ready. The irish red seems to have developed fine and I'm quite happy with the results. But the IPA seems to have developed that taste once again....
If anyone can give me a few pointers or ideas that would be awesome. I'm sure I'm not the only one who gets extremely depressed when a huge batch of beer goes south.... Thanks in advance