Starting a sump

[argan]

you have an overflow i assume? I would slowly pour the water into the display tank , letting it drain into the sump. I would go for around 5 gallons a minute adding the new stuff.

And it goes without saying but make sure the SG matches as close as you can, i did a water change the other day where i messed up and made the new water too salty, and had a carpet surfing clownfish!