Jebao GMP Powerhead Flow Rate Suggestion

While we're waiting on a custom sized tank from Waterbox to ship after the holidays (48x19x16) we decided to purchase a GMP-30 from Jebao via AliExpress. What we didn't realize is that it only goes as low as 30%. We tried it on my wife's 90CM planted freshwater tank just to see how intense the flow was at 30% and it was quite strong. We're debating on downgrading to the GMP-20, as we also have the upgraded GCP-30 gyre on the way. The GMP-30 has the same specs as an MP40, but it's hard to say if it's going to be too much flow at this point. I've seen many people running several MP40's on a 48" tank, but that also means they can turn the pumps down very low and aren't limited to 30%.

Would we be in danger of too little flow if we downgrade? Was thinking with the fish/nem guard the flow would be further reduced, but my wife is quite concerned her smaller fish will get blown around a lot.