The last 5 or 6 beers that I have brewed have all seemed to stall out around 1.020 - 1.018, when I am expecting them to get down to the 1.010 - 1.012 range. I have been pitching with White Labs California yeast, that I get going in a 1600 ML starter made with 1.040 pale malt extract wort usually two days before pitching. Though my stout made with Irish Yeast has had the same problem.
My ambient temps are around 66 degrees, and the stick on temp strips read between the 68 - 70 marks. I have let them sit for up to two weeks with no change in gravity, and I have tried re-pitching with a fresh Cali yeast starter with no luck. I have a high gravity DIPA that started at 1.100 and has only gotten down to 1.028... with this one I did a third pitching of Champagne yeast, and still didn't get any extra fermentation.
As for other information, these are all grain beers and I am airating with a filtered aquarium stone, for about 1 hour before pitching... The temp of my wort at pitch has typically been 67 - 68 degrees.
So I am trying to figure out, should I pitch at cooler temps, or ferment at warmer temps... this is really getting frustrating. Any advice would be appreciated.