Hi there, I have a Pachira Aquatica for about 1 year, and for the last two months I left the city and told my colleague to water it. The problem he watered it too much, and it developed a kind of white mold at the surface and in depth of the soil. After that some leaves started to have seome spots, the tips started to look brown and utlimately the leaves turn yellow and fall. I'll attach some photos so that you see what I'm talking about. Any help would be much appreciated, as I've became attached to my plant!
Could you include a photo of the whole plant? From what we can see, it looks fine. It depends if these are older leaves that you are losing - if so, plants are supposed to lose their oldest leaves, which get replaced by new ones. Other than being able to recognize one, I don't know too much about these plants, but that seems like a surprisingly small pot. Of course these want to be big trees, which you might not want in your office, but if you want a bonsai version, you will have to trim the roots. Otherwise, that big plant is going to run out of nutrients in that little pot. I suspect the white mold is a co-occurrence and not a cause of a problem, but I'm asking @Frog to have a look.
It looks really good. So were the leaves in question old leaves? The new leaves don't seem to be getting smaller, so maybe it's fine still in that pot.
Two of them were fairly old, but the third one was not. And beside that, newer leaves have beginning to have the same problem.
I agree with @wcutler that it is unlikely that the mold on the soil surface caused the change in the leaves. I say this because, usually, the kinds of fungi that affect leaf appearance in a houseplant are different from the kind of fungi that form hyphal fuzz on soil surfaces. Note this is a broad generalization. Also, since I can't see your soil surface, I'm making some assumptions. The idea mentioned above that water/nutrition of the plant are potential culprits, seems a sensible avenue to pursue (though I'm not able to chime in on that aspect with any expertise).
@TLH, you could start by pulling the plant out of the pot to see if there is any soil left or if the roots have filled up the whole pot. Also, after you water, make sure there is not any water pooling at the bottom of the plastic outer pot. Leaves that have turned yellow will not regain their colour. Your objective is just to make sure that new leaves are green and are the same size as the other new ones.