Perlite only, but you pour the water in from the top.
You have a solid bucket with a drain hole drilled in the side about 5cm/2" up from the bottom. Below that hole is the res.
I cover the drain hole with a finger while pouring in the nutrient solution, then release it, and I collect it to water my aloes. Some growers just pour it down the drain, making it a type drain-to-waste system.
