A few CO2 questions....?

I just have a few CO2 questions to clear things up lol

-should I use 1 or 2, 2L bottles for my DIY CO2 system for my 20 gallon tank?
-in the "bubble counter" bottle,...how many bubbles per minute should there be?
-is there such thing as too much CO2?
-is the mentioned air stone at night trick for the fish or the plants? I have a betta fish and was wondering if I needed an air stone at night for the plants.
-I am connecting the CO2 tubing to the intake of my HOB filter, will the air gap between the top lid of the filter and the water flowing back into the tank, make it that the CO2 won't reach the aquarium? (Is there a chance it will evaporate or whatever before?
-is there a way to mesure CO2 in the planted tank? (Is that a silly question? Lol)

I think that's it lol sorry i'm new at this

 

1 bubble per second is a good starting point.
There is definitely a thing as too much co2, it can kill your fish.
Having an air stone to offgas co2 is ok but not really mandatory.
The co2 piped into the HOB will work fine, but to maximize co2 levels in the tank you need to minimize surface disturbance.
Yes you can measure co2 in a tank via a drop checker.

 

Sweet thank you

 

one more question on co2...

My tank is aquascaped in such a way that both corners are heavily planted (Mostly non co2 plants) and centre is left empty with a biofilter , and hob filter...

I have DIY co2 on to left side with a lime stone attached ... will my right side plants in-hail co2 or is co2 difficult to reach other end sounds silly but confused

 

I have a 20 gallon with DIY C02 using two 2-liter bottles and my drop checker stays in the green steadily. I use a reactor for diffusion. I do not bother with an airstone at night (I worried about this at first), and the 6-12 week young bettas do not seem to be bothered by any pH changes there might be. If you don't change the bottles at the same time, I do not think you could reach too high of CO2 levels with a diffuser less efficient than a reactor.

In a small tank I believe that the CO2 should diffuse through the tank fairly efficiently, I don't think you need to worry about that.

 

Thanks Fried bettas ... I have also ordered seachem flourish excel and would be using it with conjugation to diy c02 ... reason behind I wanted to grow carpet and some more dense planting .... my daughter love watching fish & plants