small and narrow leaves

[monna lisa]

Hi everybody,
I grow under a 200 W CF 6700k bulb (added by a reflector),and my orchidarium is 120cm x 100cm.
I bloomed a Vanda and a Cattleya intermedia,both placed at 10 cm from the bulb,and a Phalaenopsis hybr,a Paphiopedilum lowii and a P. nivaeum bloomed at 100 cm far from the light,so I thought the amount of light to be quite good...
but after a year and a half of cultivation,I can see most of my plants being affected by a strange phenomenon:new leaves are dramatically smaller than the old ones;my Phalaenopsis appendiculata (40 cm from the bulb)made two leaves which are 1/2 the old ones' size,and so did my Laelia longipes (10 cm from the light),a Phalaenopsis hybr. and a Kingidium (50 cm from the light).
It seems they are all becoming dwarfs,and I can't figure why.
Have you got any ideas?Did any of you have the same experience?Light?Too much/poor fertilizer?
Thanks