hello again everybody. i have been homebrewing for 2 years now and all of my beers i like to brew are at least 1.075 og. i have issues with getting the beer down to at least 1.020. i have purchased a aerator, use yeast nutrient from white labs and keep temps around 70 but no matter what beer style it always get stuck around 1.030. does anyone have any suggestions
Do you do a starter for your yeast?
Recipe information would be important too. Are you an Extract Brewer? Mash Temps?
I learned the hard way just recently… pitch more yeast…Big beers like yours 1.075 need 2 vials of White Labs per 5.25 gal in a 1.7 quart simple starter for an Ale and 3 vials in 5 quart simple starter for Lagers…
Think about that, 8% of your ale is yeast starter and 24% of your lager is yeast starter.
I just tapped a keg this week and it was one of the best beers in a long time. When I pulled out my old notes I realized that I brewed 10 gallons of wort and pitched 2 vials in 5 gallons and a package of Nottingham in the other. The Nottingham was only of average quality but the double pitched batch was awesome and had a lower FG… The OG was only 1.058 but the FG 1.012 wlp004.
You’d be better off crashing and decanting the starter before pitching. Starter beer isn’t the greatest tasting and its better not to have it make up 24% of your beer.
Starter or pitching an appropriate amount of yeast may be the key, but more info into your process is also needed to. As was mentioned above: Recipe? Extract or All Grain (I guess that would come with recipe 
). If you are an extract brewer try subbing some plain table sugar for some of your malt extract. Sugar is near 100% fermentable. If you are an AG brewer, make sure your thermometers are calibrated correctly. Those last two keys are just as important as pitching enough yeast.
+1 to majorvices.
When I compared all 6 thermometers on my system to my new thermopen there was an 8 degree swing between them. Now I figured out why the beer was changing.
In reality it appears you are getting at least 75% attenuation out of most of your beers which is really a pretty good place to be so its not really the yeast but the recipe and the process
But 1.075 to 1.030 is only 60% attenuation (45 pts fermented / 75 pts available = 0.60). Getting to 1.020 would be 73%.
What yeasts have you been using? Have you tried Nottingham? If you still have a high FG when you pitch two rehydrated packets of Nottingham (~23 grams of dry yeast) into 5 gallons then I would think you got a mash/malt extract issue although I would have to double check a yeast pitching calculator.
Any chance the gravity reading is using a refractometer? If so, wouldn’t the high reading equate to something much lower?
Of course, we’re all stabbing in the dark here without more information.