[365seasons]

We recently got a new MH bulb, which has been heating up our tank quite a bit. Then, at night, when the light is off, the tank temperature drops. It's fluctuating from 76.9 to 78.1

What would okay parameters for tank fluctuation be?
Just wondering exactly how bad this is, and what could we use to resolve it?

We were thinking of a cooling fan. Is there any alternative measures??

Thanks in advance.