Hello; Even tho LED's give off less heat it is not no heat. You may be fine but maybe check fairly often to make sure the cover is not getting too hot.
my led lights are on 24/7, it does not heat the tank. i needed to warm up the tank to normal temp slowly before it dropped lower than 70. it is just for a night is all. i have fish that don't do well in the colder water, they need the higher temps so letting the tank sit with just an led over night is not going to keep it above 70. once it hits below that, some of the fish are at risk. they are my babies and i prefer to give them proper care and worry if things are not in their environment. i can't rely on an led light.