Jardini 150 gal tank temperature

It all depends on how hot the room temperature is and how much greater you want the tank temp to be. If your room temp is 76f and you aim for 78f. Your heater should be fine. I recommend two small heaters instead of one large one. I have a 125 and I use two 300watts on it. My basement is fairly cool however. I am guessing 68-72.

I hope you plan on upgrading your tank. A 150 gallon tank is too small for a jardini for life.