Answer: How sad to lose your orchids after repotting. In general, orchids grow and flower best when they are quite pot bound so don't repot more often than about every 2-3 years. When you do repot, choose the next size container so the roots just barely fit into the pot. Use orchid mix potting soil or even straight bark chips. Without excellent drainage, orchid roots will suffocate and die. If you decide to repot your Phalaenopsis, I've found an excellent website that offers step by step instructions and photos, too: http://www.easyorchids.co.uk/site/content/view/27/69/
I hope you find this information helpful. Best wishes with your orchids.
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