My invertebrates eat not the biofilm. Gas exchange is very difficult, what is the solution?
Gas exchange concerned me as well, you can run an air stone or power head near the surface with a timer set to turn on when the lights go off. It will cause surface turbulence and break it up and improve gas exchange at night when plants are not producing O2. There really are a number of great ideas on here to do away with it.
I have a powerhead that drives the current, as a byproduct it causes ripples at the surface which probably reduced the film and increase O2 exchange. The film may be an issue for Anabantoids as they need access to air to be healthy.
Makes sense though...HOB's discharge at the top of the water, which would disperse a lot of the waxy crud. I personally don't have any real issue with the stuff because I figure it's a product of a healthy tank, right? What does bug me about it is that I have water lettuce, duck weed, and hydrocotyle that likes to breathe, and looks simply awful with that nasty film surrounding it.
I concur - it's really gross - when I put my hand in the tank, it's coated in the stuff.