Decreasing pseudobulb size Bulbophyllum Jersey

[Kaykay]

Can anyone give me a hint of what I'm doing wrong? This is my only Bulbo. I bought it around this time last year as a young plant, and since then it has put out 3 new growths (there was a 4th but the bud rotted off). Humidity and water are good (hight) I'm feeding it with my same feeding regime as my other orchids (20 20 20 weekly weakly) Can't give you a precise light reading, but it has been outside with a very happy Oncidium for the summer, and is currently indoors for the winter living among my happy blooming phals (so intermediate end of warm temps and reasonable light) The pbulbs are only smaller than the newest of the ones before I started looking after the plant- ie they aren't getting smaller than each other, merely smaller than the peak size of pbulb. My one cultural concern I have about it other than the growth one is that there is consistently a thin layer of algae on the medium which I just don't seem able to get rid of. Maybe it's not such a bad thing.
Any insights please? I'd desperately love to see blooms on this plant next year!
Kay
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