finding a coolant leak shouldn't require any dye, it's usually pretty easy to find. Check for build-up around hose attachment points, make sure your radiator cap has a good pressure seal, check the gasket around the thermostat, and check the spigot at the bottom of the radiator.

What besides seeing the low coolant level tells you it's leaking? I mean, can you smell it? Does your heater work well? The heater is heated by flowing coolant, and if the hoses that run into the heater coil go bad, they can leak quite a bit.