Help me stop killing orchids

[janecat]

Thanks in advance for your help. I am on my 4th Phal orchid now and they all die the same way. The leaf tips start to turn dark and then the entire leaf turns a light brown, gets soft and fills with this stinky liquid.

I think I follow proper care. Water 1-2 weeks with no direct sunlight. No draft and temperatures from 60-80. I may have a lighting problem?? I have a north facing window with an awning that doesn't get a terrible amount of sun. Should I still be filtering my light? In the past I have put orchids about 6-8 feet from a grow light to boost the sun exposure.

The last one I bought (1 week ago) the very tips of the leaves are turning a purplish/ brown in a vein pattern. The moss was very moist when i purchased it and I haven't watered since. One of the buds opened up but another baby one is shriveling.

I was told with this plant that I am only to water when every one of the roots turns a grey color. Is that correct?

What else can I do to not kill this beautiful orchid?