Base of leaves yellowing and falling off when introduced to climate controlled enviro

[OzPhal]

Hi everybody,

I've recently introduced my Phalaenopsis seedlings to a climate controlled growth chamber where i control lighting, humidity, temperature, light cycle, air movement etc. In their previous environment they were receiving less than optimum light, temp was less than 20oC as we're going in to winter and the humidity was still up around 70% with high air movement. In their new environment they're experiencing a stable temperature and humidity and a 12hr on 12hr off light cycle - lighting was initially around 1,320 ft candles but i've dropped this back to 660 ft candles and will steadily increase to the 1,320 ft candles. I initially had the temperature at 28oC but have since reduced this to 25oC as the shock change from their previous environment to their new one would have been over a 10oC difference. In any case on some of the seedlings the very bottom leaves on the plants are yellowing at the base and then dropping off. Is that normal? Is it simply an adjustment to the new climate? Also, one of the leaves on a P. bellina copped a little damage in the move - it appears that the damage has spread over the leaf a little - it's now stopped though. Should i leave the leaf on there or remove the damaged section? I've attached some pictures of the yellowed leaf, the damaged leaf with a black spot forming and also an overall picture of the setup that i have. I have in there:

* P. bellina
* P. schilleriana
* P. venosa
* P. Brother Peter Star
* P. Yu Pin Pearl
* Dtps. Kenneth Schubert