I am using those in my turbogarden, in the grow tray, to add air to the roots. I also use 6" air stones in all of my reservoirs. From what I've seen, the 6" air stones work better. When I say better, I mean they bubble more prolifically. The flexible ones tend to clog easier. That's just my experience with them. Hope this helps.

I've been at this for years and I no longer even use stones. Eventually they ALL clog with something.

I grow tomatoes using DWC and just let the bare hose bubble from the bottom of each container. Seems to work just fine!

Air stones/hoses just break air bubbles into a smaller size so they diffuse more quickly. Any air in the nutrients, no mater how you put it there, will work.

I quit using plastic wands because they plug up quickly.

I can understand that you would want your air bubbles to break the surface directly under your plants, thereby splashing solution onto the roots rather than having them all break the surface in one corner of your 20"x36" container. I read somewhere that someone used a piece of 1/2 inch soaker hose glued in the bottom of the unit. It didn't cost him anything as he had it laying around and he claimed it doesn't clog. I haven't tried it but it sounded quite resourceful.

I like my hydor ario 4 submersible air pump, lots of nice small bubbles and doesn't get clogged up, more expensive in watts and price though.