I think there are many reasons for this. Let me go back through time...
When I had my DIY CO2 about 1 month ago, I got about 1 bubble per second but it was very inconsistence. I had only a few plants, which include a big patch of riccia on the rock, java fern, rotala indicia, and three tall lucky bamboos. Even though at the time, I had a lot of pearlings on riccia and java fern I also had GBA and BBA all over the tank. I think this is due to low and inconsistence level of CO2 but excess fertilizer. I tried spot treatment with H2O2, indeed the algae were reduce after several days, but so did my riccia. My tanks turned into one big mess because the riccia started to fall apart. Some of the algae survived so I decided to stop dosing PMDD and reduce light time for two weeks. I decided not to go through this trouble again and bought new filter system and co2 system and start fresh. I also bought a big patch of riccia in this forum and a big plant package, which I thought was much more than I needed, last week. So currently, I don't think I have enough fertilizer in my tank. I decided not to jump start the PMDD, but use my normal daily dose as recommended in this forum.
So far the plants seem very healthy after the CO2 system added. Not so much algae with the help of my new SAE's and aminos. The fishes are healthy, but keep hiding behind the rock and plants. They seem to take turn to come out and play. So think about it, the tank condition is better than I expected. I just like to see the pearlings to add a little excitement in the tank, but if not I am okay with it.
About CO2 saturation, I don't think this is an issue. If you recall back to my story earlier, the riccia pearled with a DIY CO2 with glass diffuser.