I have previously posted details of my personal experience, so I am not going to reiterate details. Please feel free to read my Wall.
However, in this post I will mention the basic details so as to help answer the question of; "Age And Enema Volume."
As previously posted, enemas were not a routine practice in my household, so I was only introduced to them (they were introduced to me) in a hospital in Rome when I was four years old because I needed to undergo eight surgeries at six moths intervals up to the age of eight. Apparently, for that time and place it was still a standard requirement for a patient to have a enema prior to surgery, or at least that was the way it was done with me and the other boys who were also scheduled for elective surgery.
However, because it was not always the custom to dignify a child patient with any knowledge as to what was to be done to their body, the nurses who gave me my enemas never explained anything to me, and I do not recall any of them explaining anything to any other boy. Therefore, I can only speculate based on my surviving memories and knowledge gained over many decades of personal experimentation (self administration) with enemas.
Consequentially, I believe that those enemas administered to me in that hospital would have been around 200-250 ml in volume, and I don't think that the volume was increased as I got older because it felt like they always took the same amount of time to administer. Also, they were given to me (and the other boys) whilst in the vertical position using a colon tube attached to a suspended glass/plastic canister via a long hose. Thus a 200-250 ml dose would have been the practical amount of volume that my young small colon could take in that position, and a sufficient volume required to flush out the last 1/3 of it. Those enemas were only designed to force us boys to go to the toilet and discard the remains of the previous breakfast and lunch which by then would have been loitering in the lower sections of the colon.
There was one time when for several reasons I was given an enema with a bulb for which I believe I was given more at least 500 ml, but I am not able to substantiate that volume because as usual the nurse never provided information.