I currently have a 55g freshwater tank with two clown plecos and 5
bleeding heart tetras. In addition to the fish I have recently added
few live plants (green cabomba, moneywort, anachris) of which I have
been told that my lighting conditions should be sufficient.

I have been reading about diy CO2 injection. My understanding is that
with enough light & nutrients CO2 injection will help plant growth. I
would like to try this but I am concerned that my pH will crash.

My KH is two degrees, the pH at 7.2. I have read many conflicting
reports about when a pH crash might occur.

Can anyone help clear this up? I dont want to risk my fish health in
order to help the plants.

Also, if you have a recipe for the CO2 system I would greatly
appreciate it.

Thanks for any advice you can afford.