I have a 5 gallon keg that I have filled with approximately 4 gallons of liquid. The keg has an inlet and outlet fitting for gas carbonation. The inlet fitting is shallow and the outlet fitting goes all the way to the bottom of the tank.
My normal carbonation process is done through a pump connected to the keg moving the liquid around and this pump is also connected to the gas cylinder pumping 10psi of CO2. The keg with the liquid is equilibrated after ~3 hours. The pump sucks up the liquid from the outlet fitting going through 10psi of CO2 and is pumped back through the inlet.
I want to know how long this process ought to take if I do not run the liquid through a pump with CO2 and straight out connect the CO2 to the outlet fitting to carbonate from the bottom up. I can also do it through the inlet fitting but I think carbonating from bottom up might be faster.
If i do it this way I'd need to be rolling the keg once in a while during the carbonation to equilibrate. If I had a pressure gauge I could connect it to the outlet fitting and see where the internal psi stands after some time. Unfortunately, I do not have one.