Plug the skimmer and turn off the motor.
Pool lamp leak.
If the water stops at the light the leak is probably at the light housing.
If you find yourself adding more than a quarter inch of water per day or more than two inches of water per week you may have a leak what may help is knowing what the 5 common causes of pool leaks are.
The bucket test works by applying the same water conditions in your pool to the water in a bucket.
Eventually your pool will need maintenance.
This allows you to very easily check if water is lost at the same rate.
Run the pool on the main drain only to determine if the pool light is leaking.
Because the point where the pipe connects to the light niche is not sealed water can enter the pipe.
The heavy gauge rubber ring acts as a clamp seal that waterproofs the joint between the lens and light housing.
It s an unavoidable truth with most things in life.
This part is also called the housing gasket.
In the case of leaking swimming pool lights you can use a big handful of pool putty about half a package in order to build a cone around the point where the light cord is placed.
However this is not recommended underwater.
If the pool is losing more water while the pump is running the leak is on the return line side of the system.
A leaky pool light stems from a bad lens gasket.
If the water drops below the light then there may be a leak in the drain at the bottom the pool.
The place that the swimming pool light will most likely leak from is where the cord of the swimming pool light goes through the light niche and into the electrical conduit.
You will also need to close the pool for a day.
Chlorine exposure or old age can deteriorate the rubber to warp so that it allows water to reach the light internals.
Inground swimming pool lights are prone to leakage from the conduit which is the pipe that carries the light cord from the lamp to the junction box.
If the water stops leaking below the top of the light you should check the fixture.
You can also use another method consisting in using a silicone product.