"Micro Algae Grow" fertilizer- safe level for hermit crabs?

[Tired]

I have a large piece of dry rock that I want to try to grow a ton of algae on, by putting it in a small tank with Micro Algae Grow fertilizer and a piece of algae-covered live rock. I also have a new hermit crab that I want to stick in a QT tank for awhile, just on the off chance it has ich or whatnot on its shell. Since they actually carry around hardscape, it's not just their own exoskeleton.

I figure I can probably put those both in the same tank. What level of this fertilizer is safe to use with hermit crabs? Same instructions as on the bottle? It's the stuff that has everything you need to grow algae, including phosphates and nitrates.