Well the CO2 has certainly had an effect.
Almost as soon as I switched the lights on today the anubias and java fern started pearling. The riccia has produced a few small bubbles but not much, I'm guessing light might be the limiting factor there. No sign of any from the other plants.
It also seems to be causing some fairly significant pH swings... it was around 6.5 before adding the CO2, when I checked this morning before turning the lights on it was bottoming out the API test drops, so 6.0 or below, no way of telling without a low range test. Back up to 6.4 now after 10 hours lighting. Should I be worried about this? Tap water looks to be around 7.2-7.6. I don't have any water hardness tests but the water supply down here is generally pretty soft.