Need to know more about your tank to know why they stay high. my uneducated guess is that you have mainly softies and are doing some type of dosing schedule?
I think your alk should be a little higher but I always get confused with alk to tell you the truth.
I have never worried about phosphates unless I had an algae issues, with your mag that high, you probably dont have a hair algae issue (hair algae is commonly treated by raising mag).
I agree that you have a very nice collection. I have always liked the candy apple reds because of that metallic color.
i dont dose anything i just do my weekly water change. and yes i have all softies in this particular tank. ive got a little HA problem but it stays mostly on the filter sponges. and thanks for the comment