Welcome to TRT!!
850 GPH for a 65 gallon tank is not much.
For soft corals you may not need 40 to 50 times the tank volume (2500 to 3200 GPH) but good flow reduces detritus on the Live Rock and retards
nuisance algae growth.
Depending on you budget and type of corals, you can use multiple power-heads on a wave timer on have constant flow through the LR. Or a combination of both, which I use on my 90 Gal.
I would personally start with about 2000 GPH total flow for soft corals, use the CA for flow the LR( two would be better) for now and consider purchasing a couple of power-heads for circulation.
JMO
Doug