I'm pretty positive Lloyd has been seeing his reflection in his tank and that hasn't been helping with his aggressiveness. so I put cardboard on the three sides. is this safe to do?
That is alright to do, if it gets wet or soiled replace it. Other than that, Bearded Dragon's feel more secure when they can feel safe in a "Cave" and only worry about what is in front of them/their Viv, so it will be a plus to make your Beardie feel for secure as well as less aggressive towards his reflection.
Could buy the plastic cardboard you can find with the yard signs at any hardware store, might look better to the eye. Even fish tank backgrounds would be nice if you find a nice desert themed one.
More so to block on light from the outside of a glass tank or to provide security. Background usually for personal eye appeal.
In this case the Bearded Dragon is seeing his reflection on the glass from the light emitting from the inside of the tank, as glass acts a mirror when light emitted from the inside the greater than the light upside the tank, in order to prevent this mirror effect you need to place a non-reflective object, this case cardboard, in front of the reflective surface, the glass.
Can anyone recommend a good enclosure I could purchase for my dragon? One that has walls on the 3 sides instead of glass. I'm not very good at diy jobs