The neon tetra brawl was a nice bonus

I instituted something similar in my most recent tank. Multiple layers of clay and porous rock substrates beneath and above the soil, with a sand top layer. I specifically used crushed brick, as it's terra cotta based and even higher in iron, more thoroughly baked in order to reduce breakdown over time, and naturally porous moreso than other options to foster more bacteria. I believe it will last a very, very long time.

Can we use sand as last layer?

Do you use an ugf and slow-moving uplift tube?

Hi Jay, I just saw your video, fantastic information's, I am following Dr. Kevin, Mrs. Salty and Shaun of Australia, I have no words to thank all of you for showing this fantastic process of filtration with extremely low cost, for us that love this hobby.

I am only just finding his videos now , and just implementing the anoxic filtration myself so I hope I get the same results 🤞🏽 glad I found your videos as well and hear your views. 👍🏼

Those bubbles coming out of the substrate could also be N2 - since nitrogen gas is the end result of the nitrogen cycle

Nice setup

Walstead method.

I have found that cat litter is incredibly inconsistent, for half the people it turns to mush. I think it's got to do with how long its baked. I've found that saf t sorb, used to pick up spills is the same clay but much harder and larger pieces, theres also another brand called oil dri,  when I tried special kitty , I could never get it to rinse clear and it had a slimy feel. The other stuff worked much better and I like the color better too for use as a substrate, it's more brown where cat litter is gray.

How do you have the canister filter set up?

It doesn't look "dirty" , it looks great. I don't get the sterile look some aquarium keepers shoot for. That's not what fish live in in their natural settings. Water parameters and fish behaviors/appearance primarily determine whether a tank is "dirty" or "clean".

amazing video. you sound like Father Fish in his channel. thanks.

The idea of cat litter in the planted aquarium has been around for decades.  Some points:

1)  Most clay cat litters will harden water because of the other ingredients in them.  There are exceptions, but they should be tested by immersing them in a weak acid to see if they react.
2)  The consensus is that soil, in whatever form (including mineralized topsoil), are not sustainable.  Without getting into specifics, they work well in the begining, but the tank has to be torn down eventually because of it.
3)  Ordinary gravel is usually perfectly fine.  Heavy root feeders should get plant root tabs, and I know you mentioned them here.  If you don't want to pay an arm and a leg for root tabs, use Jobe's spikes for ferns.

All-in-all I think the deep substrates you experimented with and that Father Fish discusses at length are a much better idea.  Though I would not use silica sand in mine.  Laterite is also good to mix with gravel, if you can afford it.

Do you use Plenum in your tank

Could you please recommend what kinds of cat litter

Can u not just use florist red as it is made of clay and iron rich
Because I live in uk and it is impossible to find natural clay cat litter

What is your kitty litter made from. In South Africa it's bentonite clay. Is that safe for aquariums.

nvery interesting. I have instslled mine 10 days ago, my cycle has not finish yet.  Do you have an undate on how the substrate is working? Thanks

I got special kitty cat litter from Walmart but it just kind of seems to get a little mushy is that kind of just the way it is I’m not sure