My Serissa is failing, I think....please help!!!

[Donkeywaffle]

I've had this tree for about 3 weeks now and everyday there are more and more yellow leaves or more brown tipped leaves. I have been watering it right (wait till its almost dry) and giving it sun + full spectrum light bulb (150W 18" away, was 14 hours a day but now at 4) and there is a fan not blowing directly at it but getting some air circulation going. I also have it on an humidity tray while the pebbles are always kept wet (the tray is a clay square dish that is glazed over with a copper looking glaze) and I live in bend oregon and the tree sits below the south side window getting a moderate amoount of sunlight a day.(could this problem be the change of seasons?) oh and my room always has a window open.

[ynot]

oh and my room always has a window open.

Serissas are not comfortable [or happy] at sub 50f [Roughly] temps.
I see it has been in the [url=https://www.google.com/search?hs=X4E&hl=en&lr=&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial&q=bend%2C+oregon+weather&btnG=Searchurl]upper 30s there[/url] at night.
Close your window and hope it is not too late.

[Dependant on how long it was subjected nightly to those temps.] With some proper care you may save it.
Google 'serissa bonsai care' for tons more info.
ynot