So I get the basics on how to actually make the co2 reactor and either gonna buy a diffuser or use the chopstick or cigarette filter method for a while.
But.... I do run an airstone in my tank for the benefit of the fish
The tank for me is more about the fish than the plants but I would like the plants to be in better condition and grow faster etc so I'm thinking DIY co2 to start. Will the airstone running cancel out the co2 I'm producing? Is it normal to run both?
And as far as Turning the co2 off at night I have been reading that people run an airstone at night to avoid gassing
The tank is just under 200 litres and I'm thinking a 2ltr bottle
Is there any benefit to using 2 1 Ltr bottles instead of the single bottle as some designs use 2 some use 1 ?
Keep the airstone off during the day and only have it on at night. As plants only absorb oxygen during the night, this will prevent your fish from suffocating due to deoxygenated water. CO2 is also unnecessary at night because of this.
I believe the aeration will cause the CO2 to exit the water. It's better to only put it on at night, when it's necessary. You could always just keep it on in the early morning/later afternoon if you want to watch it.
Having increased surface agitation will increase the surface area of your water, and subsequently, the rate at which CO2 diffuses out from your water.
This is why it is recommended that you have the air pump off if you intend to be injecting CO2. However, even if you keep the air pump on, you can compensate for the increased loss of CO2 by injecting more (it just means you will require more bottles).
As for the bubble rate, there are too many dependent factors (such as method of diffusion, whether you intend to use your air pump or not, etc).