I see a couple of things. Not sure if my answers are correct...
1) White spots on the leaves look like mineral deposits from water drops. This suggests that you may be misting the plant, and the water is high in minerals or salts.
2) Yellow then brown, starting at the tips and edges, and working its way up the leaf. This suggests any of several things:
a) Natural old age of the leaf. If this is just happening to 1 or 2 leaves now and then, ignore it. Clip off those leaves. If it is happening to more leaves, then it is not simply old age.
b) Salts in the water will make the tips and edges brown in that pattern. Given the possibility of high mineral content in the water (from observation 1) this may be part of the problem.
What I would do about it:
About once a month water the plant in a way that will get rid of these extra minerals in the soil. If you can flood it and let it drain a couple of times that is the best. Another way is to plunge the whole pot into a bucket of water and hold it there til it stops bubbling, then let it drain. This would be particularly helpful if you could use rain water, or distilled or other water that has the lowest possible mineral or salt level. But ordinary tap water will work.
The rest of the time water from the top of the soil and catch and remove the water that drains through. Never let it stand in this water.
