This is going to sound like a dumb question, but I have a horizontal aquarium style fixture with a plastic lens cover, inside houses the lamp fixture. Is it necessary to remove this lens fixture in order to get the full spectrum of UVB AND UVA lighting? I'm asking this because (and here's where I feel dumb) it tells me on the lighting fixture itself, in order to get UVB and UVA output, I need to remove that lens. But it seems like it would keep water, dust out and keep the light tube in place and secure. And I've seen other lighting fixtures that have the lens on.