Bubbles from pool light


Active member
Apr 30, 2008
So I fixed my pool light, or so I thought..... When I turn it on, bubbles start to come to the surface. Could this be because of heat and nothing else? I do not think there is an air leak on the seal because it has been submerged for 10 hours prior to this turn on. It ONLY happens when it is turned on. Any ideas?


Well-known member
Sep 7, 2007
Lafayette, Louisiana
I would be very careful with this...

Electricity breaks down water molecules into little fizzy streams of hydrogen and oxygen. That means the electricity might be making direct contact with the water you are swimming in, probably through the metal bezel around the light. Usually this would trip your GFI breaker with A/C current.

Are you sure this only happens when the electricity is present? What was wrong with the light originally? How did you fix it? I really doubt that light can boil water, but maybe it's heating the air inside the light and forcing it out as it expands??? Do the bubbles persist forever?

Just my 2c...


Active member
Apr 30, 2008
It only happens with power. It had a loose wire in the junction box so I fixed it and it worked. When I first turned it on, it was a steady stream of bubbles that turned into one every 15 seconds or so. I shut down after a few minutes so I do not know if they would eventually go away or if it is forever. But I also placed my hand on the ring and the surrounding water and I did not get zapped.


TFP Expert
LifeTime Supporter
Feb 23, 2008
Denton, TX
This reminds me of that experiment in junior high physical science where we applied an electric current to a piece of zinc under water to create pure hydrogen gas.

This cannot be a good thing in a pool.

As belldiver mentioned, your GFCI doesn't seem to be tripping the circuit and water is getting where it shouldn't be.


Well-known member
Oct 5, 2007
Philadelphia, PA
Electrolyzing water requires a DC voltage. Assuming your light works off standard US power, it's 60 Hz AC. I don't see how this could electrolyze water into hydrogen and oxygen. (We can go into the chemistry, if you like.)

What I suspect is happening is that there is a small leak into the fixture. As the light heats up the air inside is expanding and being forced out. When the light cools, water will be sucked in. This is a dangerous situation and must be address immediately.


LifeTime Supporter
I don't mean to say this may not be dangerous, but if ther was a lot ob bubbles at first and then just one evert 15 seconds, it's likely from trapped air being heated. Electricity splitting up the water would not have been producing more gas when first turned on than 15 minutes later.... I'd try to leave it on (nobody in pool) for a number of hours and see if it stops (once the light reaches maximum temperature).

Am I right that behind the light is typically flooded with water? If so, there's no place for the air to be hiding except that it must be getting into the bulb-casing itself.

My guess is that the back of the light was not put on well enough after the bulb was replaced. This hot gas beingn forced out will suck water in when the light cools. This is not a great thing to have... (I'd bet that you are starting to see some water begind the lens)

my 2c also.



Active member
Apr 30, 2008
It was about half filled with water. The light fixture appears to be old so when I get some extra money, I am going to replace it. Until then, breaker is off and it will not be used. Thanks!