Ric, At a max depth of 8 ft if this means 5-6 ft depth common and as wide open as 36 acres is, you may not need any.Shallow being the potential key here.At sea level and 95F you can still have 6.9 ppm DO.If I have not had any DO problems I may not be too concerned, If you are not sure invest in a DO meter and do some testing on those hot days. Wind action on shallow lakes can aerate a lot, Ted