Review on Enhance Your Aquarium's Filtration with Fluval Biomax Filter Media by Crystal Kong

You won't find cheaper at Petco or Walmart. Great carrier, Prob takes 2 cartons to fill a canister tray but they last forever so it's worth it. Excellent support surface, very porous. This is almost half the cost of stores. I also use thoroughly washed lava rock as a carrier in my SunSun canister. About $6 for a large back of a small red lava rock. This is the best media to put in your filter, it lasts forever and works wonders for my crystal clear 55 gallon tank. These rings added a nice touch, but lava stone works just as well, if not better, and at a fraction of the cost. 1 small box of these o-rings can buy you a lifetime supply of small red lava rocks, they will never break your withers. Just remember to rinse the lava rock well in a bucket with a hose, no need to boil it. Just rinse well in cold water and never mess with it again. Excellent stuff.