.05 PO4 is the issue.
That needs to come up to around 0.1 or higher.
The idea behind increasing nutrients is to grow algae to outcomepte the dinos for space. Yoiur not going to grow much algae at .05. If you read the massive dino thread, you'll see this is the typical recommendation.
Depending on the test kit your using, that .05 may very well be within the margin of error for the test and actually still be 0.
Are you sure it's dino's and not cyano? By the description of it not being on your rock and only the sandbed, I wonder if it's dino's at all?
Dino's typically cover everything, and do not just stay on the sandbed. Cyano on the other hand, can and will stay on the sandbed if your sandbed is a nutrient sink.
I've dealt with every form of dino's over the years, that's how I know how to treat them.
Pics of the tank would help get a correct ID. And if it is truly dino's, the microscope will get a proper ID on the type, and then you can form a battle plan.
While vetteguy usually give solid info, I completely disagree with his assessment of dino therapy.