In my estimation, Jefe's post (a couple or so upthread) is right on target & worth reading a second time. Poor soils that remain saturated for extended periods cause a cyclic death and regeneration of roots that start with the finest roots first. The longer the cultural conditions remain unfavorable, the larger (incrementally) the roots are that succumb to saturated, anaerobic conditions. Often, so many roots die that the plant is virtually a large cutting. The lack of roots and compromised root function/metabolism makes it impossible for the plant to absorb enough water to replace transpirational loss, and leaf margin/leaf tip necrosis is often a primary symptom with low humidity contributing to symptoms as a secondary cause. In the case where high levels of salt in the soil are causal, the salt makes it difficult for the plant to absorb water. There MUST be a higher concentration of solutes in the water inside of cells than there is in the soil solution or water will not pass through cell walls (osmosis) into cells; and, again the plant would be unable to move water sufficient to replace transpirational losses. Leaf margin and tip necrosis would again be one of the primary symptoms. Prevent the saturated soil AND salt build-up by using a structurally durable and well-aerated soil that allows you to water often and profusely. Al

Here's the other plant, a Pothos, under the other Solatube in the kitchen. There is no other exterior light or window in this space. The nearest window (facing east) is 20' away and has a 6' covered front porch and 100-year-old giant oak trees in the front yard shading the house. So, these plants are totally supported by the light from the sun-tubes. I'm pretty impressed! I had tried to research to see if they would project the right kind of light for plants since they do you a polycarbonate dome of some sort, but didn't find much written about it. Quite apparently, it's enough light for easy plants such as these. I'll post updates of them in the next few months to see if they keep faring well.

Alyssa, try soaking the plant for at least an hour. When I grew orchids in NY, we dealt with dry, low humidity air over winter. The heat in the house dries everything out. You could use a vaporizer near the plant to increase humidity, but the more important thing to deal with is the dry bark. Until those roots can take up moisture, the dry air is sucking life out of those roots and leaves. Try the soaking method until the bark begins to stay moist for at least 3 days. That should begin to hydrate the plant. Make sure your Phals are getting bright light this time of year. You want to stimulate growth. Do not keep them too shaded. Your plant should begin to grow again. Good luck, Jane

Any spray on general purpose cleaner....