hello all i live in southern florida it is around 90 to 95 degrees outside daily and my house is 78 daily , the water in my tank is always around 79.5 or so never lower but when the cooler months come my windows will be open on the house do yalll think ill need a tank heater and how big or how many for my 75 gallon tank

Have you checked to see what the temputure can reach at night?? this can drop a long way, And while you are in a warm bed your fish may freeze. I would put 1 just incase and as you said the temputure may change in winter months.your best bet is to keep a constant temp. the bigger the heater the more ecconomical they are but as you are in such a warm place it will remain in standby most of the day.200watt should do.1 will do the job but you will need to keep check to make sure its working. 2 would be better but as your use is only incase it gets cold just the 1 maybe all you need. if you check temp at night and winter and the tank temp never drops below 78 you could do without any.

ok ill check it tonite or early in the morning and see if the temp drops thankyou very much