Random flow generators (RFGs) are typically intended to attach to the outlet of a pipe, and rely on a pump producing some pressure to achieve the desired effect!
To clarify; your power heads employ a propeller style pump, these are very effective at moving lots of water for very little power. However, they are a high volume, low pressure pump, they only work for mixing water!
For a RFG to work properly, you want an impeller style pump with a pipe/tubing outlet! — these impeller style pumps are higher pressure, lower volume relative to propeller pumps. This makes them ideal for use as return pumps, the outlet of which can employ an RFG!
TLDR: You will need to use an impeller style pump to create enough pressure for the RFG to effectively function!