I know of stocking rates as high as 40 lbs to the acre without issue. I have never had anyone want to spend the money to stock more than that. For most it is a budget issue rather than an issue with carrying capacity. If you were to stock 36 lbs to the acre, I would expect your BG population to explode this year allowing you to cut back to a more pallatable amount to the acre next year. Even 20 to 25 lbs to the acre is a bunch. I tend to work with owners with larger ponds and lakes and when you start adding 20+ lbs of tilapia to the acre to 30+ acre lakes it gets expensive real fast. If your budget allows you to stock 36 lbs to the acre on a 7 acre lake, I think you will have little downside and lots of upside. Thumbs up!
Why do you stock them at different times?