Vanda health query

[Surjasama Lahiri]

Hello all,
I recently acquired a couple of Vandas from a local shop that were selling it at throwaway prices. The conditions of these plants were not the best of quality. I however, went ahead with the deal and took care in potting them properly and setting their place up. After a week, both the plants started showing yellow leaves and in one particular, it was 5-6 leaves turning yellowish. I relocated it to a more shady location and have kept it there since. The other plant is doing ok, I guess.

Can anyone help me with the above?

Here are the conditions that are currently there:

1) Humidity is more than 50%
2) the temperature range varies from 28-17 degrees Celsius.
3) I water them once in the morning via the atomizer (spray) and a quick spray in the afternoon at about 1 PM. Sometimes they get a quick dunk in the morning, every few days.
4) Fertiliser is N-P-K (20-20-20) and is used every 3-4 days.

I'm attaching some photos. The more-yellow Vanda is in the ecosystem (to help in more humidity) and the other one gets a little more sun. They seem to be developing new roots despite their conditions. Is that a nice sign?

As much as help possible guys. Thanks!!