Quick Fluval FX6 setup with Seachem Matrix. Wondering why Chemical media goes in the top tray? I’m sure you’re not alone. There’s a good reason! With the FX6’s uncommon path of water, chemical media, which traditionally goes after bio-media, would go in the bottom tray of the FX6. Due to the FX6’s capability of running for a very long time in between full filter cleanings, and Matrix’ capability of housing anaerobic bacteria, you don’t want to have to pull all your trays out of the basket just t