Not sunburn, I'd say.

Generally, when the tip of a leaf is affected, it means that root-tips are also affected.

So the question is what's going on with the potting mix, the drainage, and the roots?

Josh

I haven't seen the roots... I bought this tree maybe 2 months ago and haven't re-potted it yet. I was busy re-potting my succulents! ;D But it seemed to be growing so well so I didn't bother to re-pot it, and now, weird gray leaf. I guess I need to get in there huh?

Josh - what kind of soil would you recommend for a pachira?

A very free-draining mix, Carolyn, not anything peat-based like Miracle Gro.

I use a mix of screened bark, red lava rock, and perlite. It works exceptionally well. If you can't make your own, a decent start would be a fine-grade Orchid Mix with additional perlite added.

Josh

Thank you both, I have some perlite already so I'll be on the lookout for orchid or cactus mix :) nothing peat-based! ;P

Oh one more question (for now, haha) if the roots do need pruning, should I let them dry out and callous like I do for succulents? Or is that not necessary for trees?

I've never worried about letting any pruned roots callous over. I don't think it will be much of an issue. In fact, I would be more worried about its roots drying out too much. I would just prune away any unhealthy roots [if needed], and then just repot it right after you're done. Pachiras aren't too finicky about having their roots disturbed. But still go easy on them.

One trick I've learned over the years for removing old soil is to take my plant outside and just blast it away with the garden hose sprayer. This washes away all of the old soil while not even damaging the roots in the slightest. Even with the sprayer on at full blast. Once that's done, I just gently "comb" my fingers thru them, slowly getting them untangled. Afterwards, just repot it back up, using the newer soil.

As for the Miracle Gro soil, the only kind I ever use is the "Cactus, Palm and Citrus Potting Mix." While it does have some peat in it, it's still nowhere near as much as they put in their other potting mix varieties. Which have way too much. I've never added any amendments to it (such as perlite or bark), and it's always worked perfectly fine for my pachira. But on the other hand, I've seen photos of Josh's money tree's roots and they looked very substantial and healthy as well, using the gritty mix.

Absolutely do not let the roots dry out at all! You must keep them moist as you remove the old potting mix, just as Photo said. I hose mine as well. If you do have to set the plant aside for a minute or two, plop the entire root-ball into a bucket of water.

Josh