I am growing Orchid for last 3 years- mainly Dendrobium, Cattleya and Vanda. 3 months back I have purchased 2 Phalaenopsis. Initially they were fine and flowering continued in existing spikes. Earlier I used to water once in a week, but one month back started to submerge the pot completely into water for 5 minutes once in 15 days. After second time by doing so, leaves of one of the plants turned yellow. My question is whether it happened due to over watering or for any other reason. Please help.