The leaf symptoms of both of these are the same, because in both cases, the leaves are not getting enough water. In one case because the roots are rotten and not functioning, and in the other because not enough water is being supplied.

There's no way to know for sure without pulling it out of the pot and looking at the roots. However, unless you are supplying tons of light and air movement to a huge plant, it's more likely to be overwatering.

Watering should be done based on the plants need for water, not on a so-many-days schedule. The easiest way to tell if the plant needs water is by lifting the pot. A watered pot feels heavy, a pot that needs watering feels light. However, there are other methods.

I also agree that it's probably overwatering. How long have the phals been in the orchid mix that they are currently in? As bark ages it starts absorbing more and more water. It is suggested that you change the bark about once a year for this reason. Also, I wonder how big the clay orchid pots were in comparison to the plants that were planted in them. It's very easy to overpot orchids and that will also bring on root rot. You will never want to go up more than one pot size at a time.
Here's the good news. Your phals still have a few healthy arial roots so it will be easy to turn them around. First you need to know for sure what's going on so it's time to look at the roots in the pot. If they are all gray hollow and stringy than they are all dead.
Regardless of how big the root ball was in relationship to the pot at the time of planting - if your roots are dead you will need smaller pots. Clear plastic pots are best for orchids because you can see what the roots are doing. You than put the plastic pots into pretty ceramic pots for display.
Depending on how long your arial roots are - you may be able to coach a few of them into the new pot and mix. But only if it doesn't risk breaking them. If it's not practical to try to get a few of the ariel roots into the new pot than transplant without doing so. But keep in mind that those few healthy roots are supporting the full plant right now so I would give them a good soak several times a week. That gives them the chance to take up more water than a quick misting. Keep the dead roots attached to the phal for supprt in the new pot. Anchor the phal to a small stick - the kinds that come with the phals in flower. Generally they are bamboo and can be cut down as needed. I've also found that I've needed to attach the stick to the plastic pot to get the support that is needed. Putting a hole or two in the pot and wiring the stick to the pot itself before I attach the phal to the stick.
It is soo easy to overwater phals. It also doesn't help that depending on the parentage you can give two phals the same care and one will get root rot and the other will thrive. Some phals just tolerate/require more moisture than others and there is no one size fits all in their care.
Also, depending on the parentage, some phals will plump their leaves back up when they start getting the water they need while others will not. The ones that don't may "drop" the lowest leaves as a way of conserving the others.

In addition to the good suggestions given - Yes, some of the bottom roots may be dead. If so, when you repot, make sure the live roots below the plant barely fit into the new pot. You may have to find much smaller pots.

Put clean stones or styrofoam peanuts in the bottom of the pots, if there's much room between the bottom of the roots and the bottom of the pot, after you press them down just a little. Hope that makes sense.

Also, plastic orchid pots have extra holes in the bottom for good drainage. Some Phal pots also have slits around the side. If you can't find an orchid pot, get regular plastic pots with one hole in the bottom and make 4 or so more holes in the bottom, about 3/4 the size of the original hole.

If you go to a store for the pots, take your Phals w/ the bottom roots wrapped loosely in damp paper towels, then wrapped in plastic. That way, you can take off the wrapping at the store and try on different sizes of pots.

The trick is not to keep the roots wrapped in plastic for hours and not to leave the Phals in a hot car, even for a few minutes. I take orchids into stores and restaurants all the time, roots wrapped and the plant in a paper bag. :)

If your Phals are too top-heavy in the plastic pots, you can put the plastic pots in regular clay pots and fill in w/ stones or marbles if the clay pots are too large.

Soak your new bark mix in water for 24 hours before repotting. 3-5 drops of dish detergent will help the mix get "wetter." During that time, you can put the orchid roots in separate bowls of water, if the plants are already unpotted. Separate bowls in case one Phal has a bug or germ that could be transmitted to the other via the water.

New bark is very dry and doesn't retain water as well as it does later. In addition to soaking it for 24 hours, water more frequently for the first two weeks. This may be hard, esp. if you've been overwatering, but this new bark is way different from the older bark in your pot.

I just repotted some orchids in bark in 3" and 4" pots, and I've been watering them almost every other day.

Once your Phal is in its new pot, and the new bark is retaining water - again, after a couple of weeks - you can stick a wooden BBQ skewer down in the mix, close to the "stem" of the leaves. Put it all the way down to the bottom of the bark mix and leave it. Don't put it through any stones or styrofoam. You can cut off the top of the skewer, if it's too long. Just leave a couple of inches sticking out of the bark.

When you wonder if it's time to water, pull up the skewer and feel the last inch or so. Water if it's dry or barely damp. Don't water if it's moist.

Hope this helps. Whitecat8

Since I do not believe you can over water Phals, I will advance the point that it is inconsistent water supply that is the problem.

When you water every 7 days it is sometimes too wet and sometimes too dry. The roots shut down when too dry and rot when you water the next time.

Here is a a research paper from Cornell University in 1950 published in the American Orchid Society Journal showing Phals grow in water or watered every day grew the largest and the fastest.

http://www.orchidsafari.org/rotor/phalwater.html

Jerry ~ that is quite a paper. It challenges most of the Phal watering instructions given by reputedly reliable sources.

So that I can continue to mull it all over, please help me with some questions about the Cornell experiment:

~ What medium was used in the Osmunda pots? -or does Osmunda expand, when wet, to fill the pot? Though I know that Osmunda was once a medium of choice, it is not a common (or economical) offering, today, at orchid supply sources.

~ The Cornell paper specifies that the test applies to Phals grown "under greenhouse conditions." Do you know of any discussion regarding the implications of the Cornell results for home "windowsill" or artificial light growers?

Thank you for posting the link to this fascinating study. (I've found excellent information at Orchid Safari in the past). I'd like to understand the Cornell conditions and results better; if you can help me, I'd appreciate it.

Sweetcicely

Jerry, I'd like to hear more about your theory that you can't overwater phals. Could you expand on this a little? Especially, are there any limits, as eg low light conditions, old medium, etc etc?

And I shared Cicely's interest in the "greenhouse" conditions of the experiment as well as in the medium used. I also have one other question:

The watering except for Group 1 was with 1 pint of water, which I believe is less than a plant would get put into a sink with water running thru. It is certainly less than it would get when leached. Do you think the same results would hold true if the waterings were more copious?

I think the key thing is that the plants were in osmunda pots. They would therefore always have air. I doubt those results would be repeated if one were to use plastic pots. I also noticed they didn't say anything about the quality of the water.

I figured out a few years ago that i'm pretty much incapable of NOT overwatering. So i've adjusted by growing mostly mounts and for plants in pots I use clay pots (mostly) with lava rock or diatomite or LECA or combinations thereof. That way, even if I were to constantly pour water through the pots 24/7 as I'd like to do...there will always be air spaces. It really boils down to how best to simulate, in a pot, a plant growing up in a tree. I would guess that epiphytes in trees that are able to grow some roots down into the nooks and crannies where water will accumulate, will grow best. But they're also not sucking up softened/hard water like they would be in a typical house scenario.

In summation, I would say that one can water as often as one wants as long as one alters the growing method of the plant to suit the watering method/frequency.

Greenhouse conditions = optimal levels of light, temperature, humidity and air movement. I am not surprised that in such an environment watering frequency can be increased to near constant watering. The amount of water delivered per watering in most cases is far in excess of what is left to the plant after draining. In general it does no harm to oversupply water because the medium will only hold a few ounces of it after watering no matter how much you actually apply. What I do find surprising is that the authors would not even imply a connection between the conditions the plants were grown in and their results.

H