Ditto the above. Use the proper netting and you'll hardly notice the netting at all. Take your time and do a nice neat job.
Completely topless will most likely have some degree of reflection especially with properly "agitated" surface area. This can be a plus but in some instances can be very annoying.
Also take note that evaporation might increase due to the open top and you'll want to be more careful with sprays/mists/powders etc in the room where the tank is.
We're going to have to insist on BEFORE and AFTER pics