Review on 🐠 CerMedia MarinePure Block Bio-Filter Media: Ideal for Marine and Freshwater Aquariums, 8x8x4-Inch by Bhushan Barkley

Although this product is incredibly porous and theoretically of great importance - this block is incredibly crumbly even with very careful handling - on rinsing the outer layer fell off and even on the second rinse - the same it should to be placed in the slow flow zone of your sump, i.e. just before the last baffle and sponge protecting my last sump with a return pump inside. I put it on and immediately saw a bunch of granules from the block on my last sponge - it makes me nervous about my back pump but I'll report back on its chemistry results and if its delicate nature becomes an issue.