I have a 6-foot tall money tree (braided Pachira) that I water every 2 weeks. I use a humidifier but noticed that there are still lots of leaves that keep dropping (although new leaves are coming out). The leaves turn brown at the edges. It is in my house, and is exposed to indirect sunlight, close to a south window. I measure the level of moisture with a 2-foot long stick (which goes to the bottom of the pot) — it is halfway damp after 1 week; after 2 weeks, there’s just a little moisture left. I fertilizes it every 2 weeks with Miracle Gro for houseplants.
There are no special requirements for taking care of your Pachira, which is considered quite easy to grow. Although you do not need to water it very frequently, don’t let the soil get too dry, as this is one cause for the leaves dropping. From your description of the leaves, it sounds as if they are drying up.
The literature is not consistent about what the ideal watering schedule should be, which makes sense as the environment in which each plant is kept differs so much. Most references suggest that you water the plant from once a month to 2 or 3 times a month. It is important to make sure the soil in the pot drains well; you don’t seem to have drainage problems at all, and you monitor the water level frequently, which is terrific. Also, the plant should be fine at the light level you provide.
Which brings us to watering. To ensure the plant is happily moist, and to avoid the leaves turning brown, try watering every 10 days or so. And spray the leaves with water once a week. After a few weeks, you should notice fewer leaves drying up and dropping. If after a couple of months the leaves are still dropping, re-evaluate the situation (is the soil too dry just before watering, or is it getting water-logged?) and change the frequency of watering to suit the plant’s needs.
The information sheet that came with the plant suggests that you fertilize every 4-6 weeks. Accordingly, it is likely most appropriate to fertilize a bit less frequently, e.g., every 4 weeks as opposed to every 2 weeks.
If you wish, take a cutting with a few leaves to show to someone at a nearby nursery for advice, or call the nursery to see if they have further suggestions.
You may be interested in an earlier question we prepared on the money tree, which provides helpful general information about the plant, although not specifically about dropping leaves.