I have a potted mexican lime tree that is potted in 100% CHC. It was growing vigorously all year and was overloaded with blooms and small fruit. Then suddenly, the tree started losing all its leaves in the lower part of the plant. It originally was a very full robust tree full of leaves from top to bottom; However, it now only has leaves in the upper parts of the stems. It has been kept indoors all winter under a T5 grow light with my other citrus trees. Any ideas as what I can do to get it looking good again?

Other than your tree looking a little bear, the tree looks to be healthy. At this time of year many citrus varieties drop both old and current season leaves. In my greenhouse, I have been picking up leaves for a couple weeks now, but the abscission seems to be stopping. See this this. thread. As spring is just around the corner, your tree should soon be generating new leaves. link - Millet (1,040-)