This is the way I start seeds, and is the recommended method by all seed dealers.
I like the coco coir starter plugs. These are four years old and still good as new. I do not re-use them.
I use Hydroton clay pellets. I do re-use these.
Place the plug in the bottom of a three inch net pot and hold it like this, so you can scoop the clay pellets into it.
Notice that with the plug on the bottom, this will give us room to add clay pellets once the plant is larger. This will help block light around the stem.
Flush/Rinse the net pot with the clay pellets, until the water runs clear out the bottom.
Next fill your tub with tap water that has been set out to de-gas overnight, unless you have a well. If you have a well, use RO or distilled water. If you have RO or distilled water, it is best to start with that.
When the water reaches the bottom of the net pot it will be at the appropriate level when the lid is placed down onto the tub.
With the tub full of water at the appropriate level, put the seed in the coco coir plug. I use the screw driver that came with my ph pen. First, I make a new "hole" with the screw driver, and then push the seed in the smaller hole until it just barely disappears below the surface.
If you use the hole in the center of the plug, the seed will fall too low and have a harder time sprouting.
If your net pots are just submerged in the water, they will stay wet and your beans should sprout in three to four days. After a week they should look like this and be ready to move into your growing system.
If your growing more plants, use a larger tub with more holes. Move the plants into your growing system after they are a week old and start feeding 1/4 strenght nutes.
With DWC, lower the water level to the bottom of the net pot, after the sprout has roots showing from the bottom.