I use a 1000 gallons pump attached to a 1 inch hose. I usually do 30% of my 230 gallons tank in minutes
About the water temperature, first I collect the water in large rubber maid totes, I add water conditioners and let it sit for 24 hours. By that time the temperature of the water is the same as my home, and so far safe for the fish.
My fish probably are not very picky, they are large tambaquis, chocolate cichlids and silver dollars