potting compound for inground light

I jus put my new light in an ingrounf pool. old one was shot.  Had a heck of a time getting old wires out, so after reading a few posts, I took ground wire out first and this made it completely easier. Thatr being said, had to take off old potting compound to remove it. Now, I am trying to figure out a way to put something back on, like new potting compound, without having to drain pool below light. Is there anything you can use underwater. If not, is there a temporary fix until end of season, where its more feasible to drain pool that much.