Phals are very forgiving, but can show stress either it be under or over watering. The most important thing is to match your watering habits to the potting material you use. If you are a heavy and frequent waterer as most are use a more porous, well drained mix. If your orchids dry out between watering use plastic pots rather than clay and use the fine mix, use a clay pot if your orchids are on a heavy watering regimen.