I know this sounds crazy - I have a fluorescent light on my aquarium. It's on a timer, and was working as expected for nearly a year (my brother had the aquarium previously and it worked for him). Well it quit working one day, so I bought a replacement bulb but it still didn't work. I bought a second bulb and it still didn't work (didn't turn on at all), My dad replaced the ballast and switch and we thought it was working (it worked during testing). BUT when my timer turns it on, it doesn't appear to be working. I turn over the hood and the bulb has a very dim glow of orange-ish light on each end of the bulb. As soon as I TOUCH the bulb (in the middle, or anywhere), it works!! I don't understand what else could be the problem. I've re-inserted the bulb to make sure it was secure, but I can't think of what would cause it to not work until I touch it...ideas??
It sounds to me like the balast. The balast is the box thing you see in there (probably)...it is what sends the electrical current through the bulb. You will need to either get a new balast or have to replace the cover entirely.
It could be the ballast or the starter, but first check the ends where the pins go in, there might be a bad contact and not connecting properly due to condensation, also turn the tube round, it sometimes work.Source(s): Aquarist for over 30 years
Check and see if you have a starter for the light. This will be a round and twist into the fixture next to the ballast. To remove just turn and pull out. Hope this helpsSource(s): Hvac Tech
Always check to see if you have a starter that is good and sized correctly. However, most fluorescent fixtures do not have starters anymore. I've changed ballast only to find out it was a grounding problem w/an easy fix.
This problem plagued me until an electrician who maintained office buildings showed me a way to make sure your ballast is being grounded. It's worked on several lights that only came on when I touched the bulb, sometimes even getting hand close to it.
Take out the lights, take off the cover, loosen the ballast. Where the ballast makes contact with the screw or fixture, make sure the ballast is grounded & making solid steel to steel contact . I sanded or sc ɾąքҽ d some paint off of the ballast where the screw goes in to hold it. I also sanded the paint off the fixture by the screw hole to insure metal to metal contact between ballast, fixture, and screw holding ballast in place.
Most of the time it's an electrical grounding problem w/ballast & fixture. This should alleviate it. The paint sometimes interferes with grounding. Often when the ballast is screwed into place the screw takes off some paint off of fixture. Voila, problem solved. When it doesn't, try manually making sure there is good contact.
When I do this I usually put in new lamps(bulbs). If they are Alto fluorescent bulbs, I leave them on for a day to go through their break-in period. Alto bulbs are common & they work better for me after I leave them on for an extended period the first time they are turned on.Source(s): Best Electric & Hardware