Phalaenopsis orchids with pitted, blistered and spotted leaves?

[stripyorchids]

Hi everyone, I am new to orchid growing so I have no experience with pests, deficiencies or infections of any sort. Therefore I wanted to ask for help identifying what is wrong with my orchids.

There are four affected by strange blemishes, one has blisters on the new growth which appeared quite recently, another two were bought a week or two ago and looked flawless but have developed strange pitting on the leaves in the short time I have had them and the fourth has one lower leaf with small, mushy looking yellowish brown spots and the two newest leaves have what looks a bit like bite marks on them.

Phalaenopsis problems - Album on Imgur

Anyone know what this is, what caused it and what I can do to get rid of it? 4 of my 9 phals are affected by something strange that developed recently under my care and the 3 that aren't are among my most recent purchases so I am beginning to think I'm incapable of keeping anything alive