No and here is why:
To my understanding Marine pure blocks help supply a LARGE population of bacteria to break down organics (NH3 and NO2) into Nitrates (NO3).
The only way for the NO3 to leave a system is to physically remove it through water changes, Carbon dosing, Biopellets, and of course corals and Algae. With all this being said, their is one other way to remove it. Deep within sandbeds and rocks, where oxygen is slim to none, their is what’s called “Anerobic Zones” These zones house the bacteria that takes out Nitrates as well as some Phosphates.
I don’t personally believe that a marine pure block can have that low of a flow to create these zones. They are just too porous. Which means if you remove the block, the only thing that would change would be how much NH3 and NO2 you can process into NO3.
-Zack, to my understanding