I'm having a problem with all my beers regardless of style getting over attenuated. I've been raising my mash temps up to 4° above each beers style (up to 158° or so) to compensate with no luck. I've verified my thermometers are accurate with ice water also. I've also tried using some lower attenuating yeast strains with no luck also. Most of my beers whether they start with an OG of .50 or even .90 drop to 1.010-1.000 by the end of primary. I've thought about adding caraPils/dextrin malt to my mash, but was hoping I wouldn't have to. Any ideas to try or something I'm totally missing here?
Some details about my setup:
- Converted cooler as mash tun
- 60-70 minute mash stirring every 20min
- batch sparge with 170° water for 15min
- Converted Keg as kettle
- Glass 6.5 Gallon carboy with blow off tube
- usually switch to a stopper with airlock after first three days
- Appropriate yeast starters based on mrmalty calculations
- Oxygenate wort before pitching with with pure O2
- Two week primary fermentations
- Fermenting in a chest freezer with temperature controller
EDIT: After all the good answers regarding the accuracy of the hydrometer and thermometer, I went ahead and tested them. My digital thermometer matched the calibrated one at freezing and boiling and boiling was as expected 201° for my altitude/pressure. The hydrometer read 1.000 at 60°.
Even though I feel like I'm extremely thorough and sanitary when I brew I'm settling on it being contamination. I bought a stopper and air lock for my starter flasks so I can rule out foil covered starters being the time of contamination, and doing a major cleaning of all my brew equipment, hoses, freezers and whatever else... Thanks.
EDIT #2: Figured it out, I am really good about cleaning everything and sanitizing after after brew, but I wasn't cleaning the ball valve on my kettle. Took it apart and there was a bunch of black gunk in there! My next beer was spot on with the final gravity I was expecting.