It's a happy balance of cooler temps, but also higher DO. HSB under 4-6 pounds can handle very warm lower DO waters. However when they start approaching double digits, their needs almost become as extreme as trout. I think the depth and sheer water volume is the key. The sheer water volume of a very deep pond means it'll take longer for the water to heat up during a heat wave when you'll aerate only during the cooler hours of night time. You may have to play with it some and consider only aerate when air temps are below say 72 or 70 degrees... Depending on your common night time lows for your area, this may mean you aren't able to aerate enough. You may be able to tweek aeration so that you don't have a turn over in the deepest parts of your pond, just in the shallower areas. In doing this, you leave the deeper part of your area as a cold water refuge, but aerate the shallower areas bringing up the DO. You'd have to consult someone who was an expert in aeration to decide if this is even possible.
