hey guys. i bought a 5 gallon tank, a heater, some sand and some river rock substrate for the tank. i’ve had it running for twenty four hours and it seems fine, but i’ve been reading about the nitrogen cycle, im only a teen so it’s very confusing and i have no idea what to do. is it absolutely necessary to cycle the tank. i had two fish before and they both died in 10 days unfortunately. i really need help, what do i do??