The first video was actually shot after the second. The CO2 diffuser was there in both, but the air pump has been added. Although it is switched off for now. I am going to put it on a timer so that it is only on at night when the lights are off.
It's just biological CO2 for now so I can't turn it off over night which is what prompted me to install the air pump.
As it stands, every time I look at the tank I can make out very fine bubbles, although I don't know if they are just from the CO2 or if they are from the rippling at the surface.
They are so fine that they will not break the surface if the water and seem to sit there until they hit the flow and then go back down into the tank. Hard to describe properly, but there are always bubbles.
I'm happy to admit I'm a complete novice at this though so I have not a great deal of a clue about any of this lol