Aquatics Unlimited: Articles: Troubleshooting Fluorescent Lights
Image 1
Image 2
Image 3

Troubleshooting Fluorescent Lights

for the week of 4/2/98

If the light goes out in the hallway, you can usually just screw in a new bulb and in moments, you can shout, "Lux fiat!" ("Let there be light!"), and flip on the switch. But when a fluorescent aquarium fixture goes out, there may be several possible causes. Here are some troubleshooting tips:

A bad bulb will often be blackened at the ends and will start, but slowly. If the fixture is an older model with no starter (the switch must be held in to start the bulb), the lamp often turns itself off after a few minutes or hours. If the fixture has a starter (little silver can, most common size if FS-2), the lamp will often turn off, restart, and turn off repeatedly.

A bad starter will likely result in one of two extremes: either the lamp will not start at all (although oftentimes the ends of the bulb will glow) or it will start promptly, but begin flashing as the starter continues to attempt to start the bulb, even though it's already on.

In older models with no starter, failure of the four-wire switch also results in starting failure. If the starting circuit (usually red or blue wires) fails, the bulb may show a faint glimmer throughout. If the main circuit (black wires) fails, the bulb ends will glow, but upon releasing the switch, the bulb goes dark.

A bad ballast (transformer-looking device sometimes found on the cord on older models, but found under the reflector in many newer fixtures) is probably the worst case scenario. Since the ballast's job is to reduce the amount of current that goes to the bulb, a damaged ballast often results in immediate damage to the bulb. There is usually a flash of light, and occassionally even an implosion of the bulb itself. The aquarist might not be there at the moment of destruction, and assumes the bulb merely needs to be replaced. Unfortunately, the new bulb too is destroyed in seconds, and the aquarist learns an expensive lesson.

If the fixture simply does nothing, it may be any of the above, or a number of other things, including a disconnected or broken wire, bad plug, bad switch - and hey, don't forget to check if it's plugged in! Sometimes it's best to take the whole light fixture, bulb and all, into the shop and let the dealer swap a few parts until he finds the problem.

Last but not least, keep in mind that an aquarium light is a 110 volt electrical fixture sitting two inches above a container of water. Unplug it before attempting any repairs, and be sure everything's back in order before re-installing it.

Submitted by: Jim Kostich


"Tip of the week" appeared regularly in 1999 and 2000.

Copyright © 1998 Aquatics Unlimited
All rights reserved.

Local Specials

Through 10-26-17

Pond Fish 50% OFF!

Pond Plants 50% OFF!

Select Saltwater Fish 20% - 30% OFF!

Dry Base Rock $2.50 per Lb

GLO-Fish 20% OFF!

All Freshwater Angelfish 20% OFF!

Cobalt Microvue Aquarium Kits 20% OFF!

Seachem Flake Foods 20% Off!

Kent Pro Scrapers 20% Off!

10 tank $16

20H tank $33

20L tank $33

29 tank $50

40 Breeder tank $86

55 tank $105

65 tank $141

75 tank $133

90 tank $225

120 tank $365

125 tank $306

150 tank $521

180 tank $617

210 tank $712

75 Overflow tank $270

90 Overflow tank $324

120 Overflow tank $474

125 Overflow tank $461

150 Overflow tank $663

180 Overflow tank $726

210 Overflow tank $932

Aqueon Pine Black Stands 20% Off!

REWARDS account may be required for special pricing. You may sign up and use the special pricing the same day!

* = SPECIAL ORDER; 100% deposit required

** = while supplies last

*** = specially marked tanks only; selection may vary during the sale

Aquatics Unlimited | 3550 S. 108th Street | Greenfield, WI 53228
Monday-Saturday 10:00 a.m. - 9:00 p.m., Sunday 10:00 a.m. - 6:00 p.m. | Phone: 414-543-2552 | Fax: 414-543-4929