So, I'm setting up my first Opae Ula tank. It's going to staying on my desk at work, and I wanted to make sure all was well before my shrimp arrived. I've had a digital thermometer in it for the past 3 days to record any temperature fluctuations, seeing as most companies lower the thermostat when no one is in the office. As a result, I found out the water temp stays just over 16 degrees during the 15 hours a day no one is in office. Should I get a heater, or should the Opae Ula be OK?