Almost two full bags of Hydrocorn expanded clay pebbles. Each bag has ~34 lbs or 36 liters when full and the bag that isn't full only has a couple of scoops taken out of it. These bags smell a little like a basement but I've just rinsed some and used it in my tanks and the fish don't seem to mind. This is an example of the bags (no affiliation): https://www.simplyhydro.com/product/shop-product-gold-label-hydrocorn/