Change fixture in a small niche. Is there a way to replace the wire and how do I seal

I have already figured I need to lower the water level.

My pool guy did not even give me enough wire to get the fixture out of the water. Can anyone help me with a video or something that will point me in the right direction?

Lower water below niche..
Pull out old LED fixture.
Cut wire?
How does the wire seal where it goes into the conduit?
How do I remove the seal?
I can tie the wires from the new fixture to the old and I should be able to pull both through the conduit to the junction box to wire up the new one. Once that is done what do I use to make sure the wire is sealed in the niche and not leaking?

Any guidance would be appreciated!

Ted

Usually the wire to the junction is in a conduit sealed to the niche. Since the junction box is higher than the water, the conduit can fill with water up to the level in the pool, and the junction will be dry. Attached a stout pull cord to the wire at the junction before trying to pull the wire out of the niche, then use it to pull the new wire back from the niche to the junction.

But, installations vary in quality. If your conduit is well installed, this should not be a difficult procedure. If it broken, crushed, etc. it may take some effort/lubricant/digging. If your conduit is leaking below the waterline, various products can be used to seal the new wire, once it is installed.

I changed mine without lowering the water level.