My Oakleaf Hydrangea looks like it has a case of chlorosis and this is the second year it has looked this way. I have used Rose food, Azalea food, green sand and that Magnesium mix (forgot name of it). It still has very light green leaves with dark veins, but it looks like it will have good flowers again this year. I can't figure out how to get it back to the dark green it used to be. All other plants in the same area are healthy and growing like crazy. Any ideas?

It's most likely a trace mineral problem. Try drenching with Garrett Juice or aerated compost tea. Dry molasses might also help since it is also related to poor biological activity.