Paphs in S/H-->What am I doing wrong?

[wgama]

Hi I have a couple paphs that I put into s/h because I saw that they do so well and I thought it would make it easier for my parents to care for them while I was away at school. This was about three years ago now and I have seen fairly minimal growth from them. Both plants were about two year old seedlings I purchased at a show and they were in great condition.

The Paph. insigne has multiplied and grown and there are now about 4 main growing points. Unfortunately most of its offsets along the way seem to grow to about an inch high and then just dry out/die off. Most of its older leaves do this as well. They don't lean or stretch so I assume they get enough light.

The Paph. vanda m pearman has never multiplied and mostly just had a couple leaves alive at a time. It quickly loses its older leaves. Although this summer it did put on some very healthy growth.

I was wondering if this is possibly a nutrient or water issue? Maybe a build of of minerals from the tap water? Our tap water is fairly hard and they only get a bit of fertilizer when I am home.

Side note:I think I have heard of people adding epsom salts to their s/h pots? What is this for?