Interesting insights Pete. I moved the airstone under the filter
intake, and about every 30-40 seconds the output sends out a bunch of
small bubbles. Some hit the surface and break, but I'd say 30% is fine
enough to dissolve immediately, and another 25-30% gets caught under
some of the floating lotus leaves. There's a cheap diffuser for ya,
and its not even DIY! : )

I think turning off the CO2 at night makes sense also, and I think I
will start doing that. Although I have read the school that says 24/7
allows a concentration the plants can use for the morning, and
sidesteps possible ph swings. I take it you disagree here?

Thanks for the advice man.

I used to run my CO2 24x7 then read several articles at The Barr
Report site that suggested not doing this (it gives the fish a break,
and the plants do not use CO2 when the lights are off). I tried it and
the plants are growing just as well, the fish do not appear to get
stressed by the pH swing and I save some CO2 - so that's my reasoning.

Best wishes
Pete