Those plants are really taking off! I sorta miss dwc. I might just run a couple buckets this winter.
You have such a tidy setup that I almost hate to offer advise. But, here goes anyway. I found 1/4 irrigation line to be great for air lines. Two reasons:
One; the black reduces light entry, however tiny into your bucket and helps keep algee out of your lines.
Two; it's rigid enough too keep the air flowing if you happen to set a bucket on the line.
This is the stuff it's usually cheaper in a hardware store.
I would use flexible black aquarium line in the bucket and down the side, then the rigid stuff from the lower sides on. It really helped me in my less tidy setup.
You have such a tidy setup that I almost hate to offer advise. But, here goes anyway. I found 1/4 irrigation line to be great for air lines. Two reasons:
One; the black reduces light entry, however tiny into your bucket and helps keep algee out of your lines.
Two; it's rigid enough too keep the air flowing if you happen to set a bucket on the line.
This is the stuff it's usually cheaper in a hardware store.

I would use flexible black aquarium line in the bucket and down the side, then the rigid stuff from the lower sides on. It really helped me in my less tidy setup.