Flooded tubes with air curtain

I'm currently running a NFL system through two 4inch round pipes, with an air curtain in the reservoir. I'm planning on damming the end of the pipes to created flooded tubes (2inch deep).

My question is, would it be better to use an air curtain along the length of each pipe instead of in the reservoir?

I'd definitely choose for 'in the reservoir', seems messy otherwise. You can take it out the rez and clean it if necessary.

I use flooded tubes and have two airstones in the res, but my main motivation for still using them in is that they cool the rez a bit (air pump itself behind active intake of my growcloset) because it's not really needed in my case, both tubes create a small waterfall on the returning end. Got an air curtain on my wishlist but max DO isn't that heard to achieve, and a good DO is easy to achieve if you keep temps at minimum.

Here's my 'dam' (I can turn it to lower/raise the level inside the tubes)