Controlling temp

[Aquattro]

Rick, probably multiple heaters, using the built in thermostat. That will (hopefully) keep the temp up if the garage temps drop.
An external controller is just going to do the same, with a higher cost. Also, depending on the lights you end up with, you may have to cool it as well. Fans all the way to chiller may be needed to keep temp stable.

[don.ald]

I run multiple heaters now, and well I use a fan in summer but rarely do I worry about overheating.

[denny_CC]

have you looked into the turetemp controllers for heaters? might be what your looking for

cheers

denny
concept aquatics

[Baldy]

Nice thing about temp controllers is that if the heaters internal thermostat sticks on, it still shuts the power off to the heater. An aquarium controller is a better deal in the long run as it adds the function of temp controller, ph monitor, wavemaker, timer controller, ECT. Even if you don't use a light module or net module, they're still pretty awesome

[lastlight]

if you can find a dual stage ranco controller they're far more reliable than the thermostats in our heaters and handle cooling as well. ebay sometimes has them for a good price. you can probably get an entry level apex for about the same price tho.