If pulsations are your goal, add a piston pump, such as the one I have published here, to your enema bag. I have also in the past used a two garden hose system. One hose filled an eighteen gallon Robber Maid tank used as a reservoir and a second hose carried the waste water into the toilet. An 8 MM, 3/8 inch, I.D. clear plastic flexible tube is used to siphon the water from the tank to the colonic speculum, nozzle. This siphon, influent line, supplies the enema water to the speculum. The flow rate is controlled by the height of the tank above the injection point and an inserted ratchet clamp from your enema bag. A piston or bulb pump is inserted into the supply, influent, line to keep the flow and pressure to the recipient's specifications. The pump can introduce pulses into the water if desired, and start the flow by drawing water from the supply tank. The piston can also raise the pressure in case the tank is located level with or below the injection point.The other variable, temperature, should be measured in the tank as the water flows in from the mixing faucet.
You are saying that this is an open tube system which it is! A commercial colon hydrotherapy machine can also be used open tube too! My garden hose irrigator can be a closed tube system by folding the waste, effluent, hose double to shut off the flow. This way both hands are occupied and either the influent or efflluent hose is open while the other is closed. Alternately doubling the hoses is the way that I have always used this two hose system.
I have used this system from ships, hotels, while camping and from home for years. I still keep it in my mind and in reserve. However, during the past year, I have acquired a commercial, listed, colon hydrotherapy machine that I use regularly because, an enema a day keeps the doctor away!
73,
Bill/K2MMW