Circular tank will be 150 gallons. Air temp in the basement is 64 F in winter ( 17.8 Celcius), and I've noticed if I don't heat the water in my basement tanks they will drop to 62 F. (16.7 Celcius). I need the water to be in the low 50's F. (10 to 12 Celcius) for trout egg hatching, however once the trout get to be fingerlings they can handle water in the upper 50's F. (13 to 15 Celcius), and perhaps even 62 F. (16.7 celcius). I know my adult trout in the flow through pond outside have no issue with 60 to 62. F (15 to 17 Celcius) water in the summer.
I will be pumping in well water, which comes out of the ground at 51.6 F. (11 Celcius) , although it probably warms a few degrees in the storage tanks in the basement.
I can keep the water cool enough with the well water alone, but the use of a chiller and biofilter should reduce the amount of flow needed. At least that is my thinking.
I can easily monitor ammonia, nitrites, and nitrates to determine optimum flow etc.