Do you have a recommendation on how much flow for a 10 gal? That way we may have a little more success in coping your results. For my 17 gal I could manage 360 gph or maybe 710 gph, would that be enough, too much? I also don't won't to hurt my fish with the high flow. Thanks for the great write up!
Higher is better. Beyond that, it's hard to suggest any meaningful lower and upper limits. I can at least provide the tank setups used for treatments.
The majority were done in a 46G bowfront, with between 1,320GPH (Koralia clone) and 1,620GPH (Koralia + Penguin 1140 powerhead).
Some others were done in a 10G, dual Aquaclear 20 HOBs with media removed, rated for 200GPH combined.
As for fish safety, if they're stuck to the powerhead intake and can't get free, it may be too much flow.
Seriously though, they can tolerate very high flows for 15 minutes. Much higher than they could tolerate continuously, as fatigue eventually sets in from fighting the current.