Hey Good Greef, the fellas above covered it pretty well. It might help, but probably no more than your standard rubble. You definitely need anoxic zones for denitrification and you're simply not going to get it with those in my opinion.
I have two blocks of the Marine Pure in my tank, won them both at C4. My aluminum coincidentally is very high according to my Triton results but I take that with a grain of salt with their results. I will say at over 100x the recommended level for aluminum by Triton, my tank is running just fine. This is WITHOUT water changes so unlike most tanks which run water changes, my aluminum doesn't get diluted other than by GFO, which also binds some aluminum. In the end, I wouldn't worry about it.