You can, but that's not necessary if you use a submersible return pump. Just feed the tubing into one side of the sump and attach a "sock" to reduce the bubbles. Then on the other site you'll have a pump to bring the water back to the tank.
You may still have room for LR
and Sand if there's a way to separate things. LR
will be fine, but sand and macro algae will get sucked up by the pump if you don't do anything to prevent it. Look on EBAY and see if you can find a used sump that's drilled and baffled.