Seachem Matrix Bio Media 250ml

Works as advertised. Would recommend it.

just pumice stone.

The bio-medium is little volcanic-type rocks, large pea size. I’m using about half the container (250ml, so about 125ml). I’ve put the rocks into a bag, purchased separately, that fits my filter. My tank is 15 gallons and my filter runs at 200 gallons an hour (sounds crazy) so the rocks get a lot of flow. When I switched to this brand, I left my old bio-medium in the tank for about a week, so the bacteria would populate the new medium. My ammonia and nitrite are running at zero. I rinse the bag of rocks about once a week, scrubbing it between my hands to clear the algae. The rocks don’t get clogged, so I haven’t had to change them out for fresh ones. It takes time to build the bacteria population, and it’s important to keep something in your aquarium where the little creatures can live. In the photo, I’ve layered a bag of eggshells on top of the Matrix. (The eggshells raise the pH.)

Dusty at first. Give it a good rinse, pop it in your filter, and youre ready to go!

Quality item as described. Ive used this for years and it works great.

Still new to this product.

Awesome bio media!

Love it nice groves for beneficial bacteria to grow, Nice size fits well in canister , but you might wanna get the next size bottle up not much comes in the small.

did absolutely nothing haha

Good works good