Eventually the oldest leaves yellow, die and fall off. Have you checked it for tiny spider mites or other pests?

I know power leaves will shed, but I wouldn't think it would occur at such a rate. I'm pretty sure I'm spider mite free as I've never had them and the plant is located in an area of such high humidity. I'll do the paper test and see for sure.

It sounds like overwatering to me too. I lose a leaf here & there, but generally only one or 2 at a time, I'd take more yellowing than that to be a sign of trouble.

Perhaps potting it up larger was ill advised? It does have a drainage hole, right?

I keep mine potted on the smaller side; I like Pothos to look semi-crowded at least & they seem to prefer it (I keep at least 2 pots at all times, in 2 different sizes.)

M, I agree, check for mites, and/or other pests.
But I'm thinking by you upping its pot size, especially if it was accidently overpotted, may be the cause of its yellowing leaves. Moreso if you're keeping soil soggy or even constantly moist.
Remove yellow leaves to start with.
When it's time to water, stick your finger inside soil..if it comes out wet/moist, wait a few days and recheck. Only when your finger comes out dry should you add more water.
Though Pothos enjoy humidity, they do not like roots sitting in constantly wet soil.
As far as I'm concerned, over-potted, soggy soil Pothos tend to rot fast, which is why well-draining soil is mandatory. If you're a water addict, LOL, repot in a clay pot w/drainage holes.
What type of light is your Pothos getting? During summer, they don't require direct sun, but as days shorten, Pothos should be set closer to a window. Even though they're labeled low-light plants, they do best in medium light.
M, if you really feel you overpotted, I'd take the chance by repotting in a smaller container, and use a well-draining medium. Good luck, Toni

When I say "I let the mix dry pretty well" in my first post, I mean that I let it dry almost completely. When I probe into the mix w/ my finger it is dry and the pot feels light. It is in a glazed clay pot with a hole in the bottom. I repotted a few months ago b/c it was very pot bound and after repotting it began to grow very very well. Maybe my girlfriend is watering and I don't know... Its always easier to blame someone else. Hah!

M

You could be seeing delayed stress from drying out a bit too much. While it is true that pothos doesn't like to be soggy, it doesn't like to dry out completely either.

I haven't moved it in 2.5 months.

You mentioned it was by the shower, steam will add bonus moisture to the plant. Pothos like a dry out between waterings. Try a diff room :)

Hi Gigi & welcome to Houzz. I'm very curious how this 8-yr-old discussion came up in your browsing here, if you don't mind my asking. The last clickable page, pg. 165, ends in replies from 2011.