OK, to be clear, I have about 1000 photos on my mac I want to add to my iPhone running 8.1 and iCloud photos.
If I shut iCloud photos off, then I can sync via iTunes either my iPhoto library or a folder of photos.
However, if I turn iCloud photos back on, all the sync'd photos are deleted from the phone.
I guess the real trick is how to add photos from your computer to iCloud photos so they can be seen on your phone?