Phals dying, help

[Shani962]

Hello.

All of my old phals are OK and growing new leaves and stems
But all new normal and big phals from supermarkets keep dying. I get them from my friend who works there and gives them to me so they dont end in the garbage-because the are not blooming anymore. Most of them are dehydrated and in semi-ok shape. I water them normally-I soak them for 10 min and repeat when the roots in the medium are silver, usually once a week. They seem to be doing better and then the blooms- if they have them- start drying and falling off, the leaves get yellow and fall of but they are not like old leaves that are paper thin and have no food inside. These leaves are still a bit thick and have food in them but the plant discarded them. Also some times the planets axis gets soft and in one occasion it smelled like rotten potato. When the leaves fall off I tried to cut a bit of axis and its all dry inside and in most cases it gets a white mold on it.
One big phal I had for 4 months. I reported it and it started growing new roots and new leaf. All seemed great for 4 months and one day the lower leaves got yellow and also later the upper got yellow. The axis got soft and white mold on it.

I don't water them too high-only to the top of the medium- so no water can get between the leaves and axis.

Also the one in the picture had white blooms that fell off and a dark patch-wound in the middle of the axsis. Few leaves got yellow and fell off and I tried to remove the black mold-like from the stem. But the other levels were already a bit yellow and had fallen off also. I tried to cut a bit off the axis but like in other two cases it was dry inside. The stems were still green so I let them be to see if a keiki will maybe start growing. But today I saw all blooms are dying-it was expected -and one stem is drying from bottom to the top. The other in the pictures is starting to die too maybe-yellow leaf and 3 in the middle has already fallen off.

Please tell me what am I doing wrong or what could the problem be.

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