Its a pond filter sponge block available at the local fish store and also on EBay

Thanks. I figured out a few things about fish over the years and try to share what I'm doing when I can to help out fellow fish keepers.

Thanks for the reply Daryl you have a nice tank and obviously know your stuff

Terrific idea! Thanks for sharing…

What sponge is that and where did you get? Looking for something similar for my upcoming CRS Shrimp tank. Great idea with the different tube with slots.

How larger particles and excess fish food are be able to pass thru?