That looks like it's only a digital thermometer with no fan control features...
There are temperature sensitive fan controllers available, this one
for example just plugs strait into the fan (you could clip off the female connector and just use the red and black wires, yellow is just a "sense" wire used to measure the RPM of the fan).
Alternatively you could splash a little more cash and get a device designed for a 5.25" expansion bay like this
(DVD drive sized slot), which has temp sensors, LCD display, and most importantly custom settings for temperature. I'd be hesitant with this device though as once again there's not a lot said about the operation of it, ideally you'd be able to get hold of it and have a play with it and see if it suits your needs.
Does it need to be automatic? You could get a device like this
which has manual control dials for you to adjust the speed as you see fit. Comes with 4 external temp probes (you could put two of these in with your lights, two in the exhaust stream) so you can monitor the temps and adjust as you see fit.
This solution can most likely be a "set and forget" solution. PC
fan controllers are usually designed to deal with the variable heat load produced as your use of the PC
changes. Your lights will likely come on in the morning, go off in the evening, and stay exactly the same in between those two events. As long as the fans are running I don't see that you'd need automatic speed adjusting. If you have a timer set for your lights, I'd just stick the fans on the same timer so they come on and turn off with the lights.
If it were me, I'd try the fans at full speed first and see if the noise bothered me at all. They'll be running pretty much unimpeded (air impedance and turbulence is pretty much the primary cause of annoying fan noise) in that large hood, if they do bother you then I'd look at reducing the speed. You may find that running them at half speed still provides ample cooling power.