Cattleya Jongheana pseudo bulb sheath yellowing

[sweta]

Hello Orchid Pals,

I need some help with this cattleya that I purchased about 9 months ago at a garden festival in seattle. The plant was in spike when I purchased it. After it bloomed and the blooms fell off I repotted it since then it grew 2 new pseudo bulbs and I did see lot of happy sap on those 2 pseudo bulbs initially but now I see that one of the pseudo bulb sheath is yellowing. I repotted it in pine bark, watering schedule is once a week and fertilized once in 2 weeks. I used tap water during the summer months for watering but otherwise I use rain water mixed with tap water. Home environment is pretty dry and I'm growing it under grow light so its gets plenty of light. I'm not sure what I can do to help this plant thrive.