Question About reservoir temperature

[daytonajim00]

Any Fish Tank section (even Walmart) would have good drop in thermometers for 3-10$. Finewood, I was interested in temperature control as well and had a spare 1/3 HP Chiller laying around lol. My problem is I have multiple reserviors so I built a heat exchange out of thin-walled plastic irrigation line forming coils and running through each chamber via bulkheads. The jury's still out...

FYI: I would suspect going as far as adding chillers is a less common but preferable thing.