Mounting water pump inside the tank

[newhobbist]

I've just bought Jebo 36W UV sterilizer and will install it on weekend. Since I have powerfilter, I will have to use separate water pump only for UV. Since water pumps can be submerged, I'm thinking about placing it in the tank to avoid any external plumbing. Therefore, I need to know how to properly place the pump in the tank. Can I just place it on the gravel, or should I remove gravel and place the pumb directly on the glass bottom?

[greenmaji]

Power Heads have suction cups that will attach them to the glass.

[newhobbist]

Thank you.