Marineland penguin 350 too strong?
 

My betta started hanging underneath the filter, where the filter hangs on the tank and i don't know if the current the filter creates is too strong.
And I was wondering since I upgraded from a 20 gallon to a 40+ gallon tank and i move all the gravel, the water, the decorations and i put the filter media and the bio pad from my old filters inside a marineland penguin 350, how long should i leave them there so the bio wheels from the marineland filter absorb the BB?

Fish can easily swim away from too much current in 40 gallon. Unless filter is so strong that fish is being swept about the tank,,I would not worry bout the fish.
Would leave seed material in filter for a couple weeks were it me.