Picked up a used T5 lighting system for a reasonable price knowing the connections for the lights were corroded due to being exposed to an open tank and the lights had no acrylic protective cover to prevent the evaporating water from migrating above. I partially disassembled the unit to remove the contacts to clean them up. The first method that came to mind was using vinegar and let them sit for a few hrs. What a huge difference. All I'd have to do next is lightly polish the contacts with a very mild abrasive which could be a pencil eraser to a very fine steel wool or emery cloth.