Heater broke

[Javajuice13]

So my heater finally gave out. However i haven't been able to get a heater until today. temperature has been! at 65 and i plugged in my heater and set it to 77 degrees. temperature is now at 70 but has stayed there and hasn't really been heating up. I'm tempted to turn up the heater so that my tank can be in adequate temperature but i hear that you should heat the tank slow. so i guess my question is why has my heater stopped 70 when i put it at 77? and also will my fish and coral make it? i have a Frogspawn hat has shriveled up and want an idea if it has a chance to make it or not? fish seem okay.

Im new to this reef tank so thank you to all who help me with my questions!

 

[organism]

You may want to post in a different section since this is for coral propagation, but your heater shouldn't be stopping at 70 degrees unless it isn't rated for your tank size or unless you've got it in an area with very little water movement. Setting it higher won't do anything but make it continue heating the tank past 77 degrees... It's either on or it isn't.