I would highly recommend the Random Flow Generator (RFG)... for obvious reasons :beaming-face-with-smiling-eyes:
Putting my bias aside for a moment, the
Random Flow Generator is a very simply way to create flow and movement in these tanks.
The Spinstream is a good product, however it does require regular maintenance to prevented from sticking or staying in one position and it is pretty restrictive in terms of flow-through. At least more than an RFG is.
My advice would be to go with the single
1/2in RFG paired with the
19mm Slip-fit Drop adapter for each outlet.
https://vividcreativeaquatics.com/innovative-marine/#20gallonormore
Then crank that pump up to 100%. Or, if you really want to see them create waves, install two smaller pumps like a mighty jet 328 - one for each side.
With about 250 tp 450 GPH going through each RFG, you may not even need an additional power head talking up sapce. Especially if you're not considering SPS at this time
one nice thing about the 1/2in RFG paired with the 19mm slip-for-drop is that the over all size is exactly the same length as the sock flare nozzle and more narrow - so it doesn't take up a lot of room