No experience with direct injection of silicone, but i am closely watching the discussion and videos since long, as I am planning to do a tank with direct injection, hopefully this month. One thing I didn't understand, why so much pressure is required ? If you see a youtube video, when he pulls the zip tie out, the glass makes a "zing" sound.
I think, direct injection is the only method to get a really clean look.
Regarding Biomedia, I am doing some personal research
for a future commercial project of my own, if successful. (Inspired by pondguru.
). And perhaps you already know, what the biomedia will look like.
It will be a cross-breed of Biohome Ultimate and MarinePure. Problem is they are not pairing up
Jokes apart, to my understanding, depleting the oxygen in water, and then passing the oxygen-less water through filter media is the key to success. If there is not enough biomedia to deplete the oxygen, only aerobic bacteria will grow, and anaerobic bacteria will only grow if the preliminary layers of aerobic bacteria consumes all the oxygen.