Rescued free tank

I got a pic of it so you can see what I'm talking about as I'm due to change it this weekend anyways...

the intake at the bottom with gravel...the shells prevent the water from jetting through that chamber and causing a trickle/noise action after...
but if you look at the shells...they get "dirty"...whenever I switch the carbon they clear right up

Carbon will improve water clarity but I have never known it to drop nitrates.

Maybe an experiment there for anyone who wants to try it. Set up 2 tanks the same size with the same number of fish and do the same water changes, etc. Have carbon in one and monitor the nitrates on both. Maybe after a while remove the carbon and let nitrates go up, then add carbon and see if the nitrates get lower without water changes.

@TwoTankAmin ready to become the TenTankAmin?

Sorry folks, didn't abandon this just sidetracked onto a different issue.

For now I am roughly setting this up with some larger pebble stone as substrate, first stage filter is the micron sock, then in the second compartment I have a course sponge then a filter bag mixed 50/50 with active charcoal and Zeolite crystals. and then floss to top it off.

Going to fill it and run it to cycle and then my move my dwarf gourami and shrimp until I can figure out what happened to my planted tank.

Will keep posted.