VEVOR 4 Layers 72 Plant Sites Hydroponic Site Grow Kit 8 Pipes Hydroponic Growing System Water Culture Garden Plant System for Leafy Vegetables Lettuce Herb Celery Cabbage

Is this intended for continuous water flow or a flood and drain system.

This would be my first time just starting out and your system looks simple and most effective from others I have researched.  Was wondering a couple of things.  It looks like I would need to provide something like a 5 gallon buck for water source and are there any minerals that I would need to add in the source water?  One last question can this system be expanded by purchasing another one and connecting the two units together?  Thanks in advance for your response!  Wesley