I have an old pool light that the gasket has rotted out on. I'd like to replace the fixture with a modern LED color changing fixture and do the work myself. Please confirm that the new LED fixture is compatible with my existing niche. The fixture I'm replacing I've been told is an Spectrum Amerilite, and the labeling on the light says it is No. T0925168, and also see a Pentair logo on one of the labels. I'd like to replace it with a Pentair IntelliBrite LED 5g color 120V. Will this new fixture fit in the existing niche? Is it ok if I replace one fixutre with new LED and leave the other two as halogen fixtures until they go bad? Thanks.