ZeoLite stones

[Delphinus]

I don't think it's anything particularly mythical, they are basically a very porous substrate that yields a high surface-area-to-volume ratio which means it is an ideal growing ground for the bacteria, which if dosed alongside will colonize the substrate and aggressively scavenge the organics which would otherwise biodegrade into nitrates and phosphates.

It's essentially the same idea with biopellets except those are polymer based and dissolve slowly over time as they are themselves consumed by the very bacteria they host .. except since the zeolites are more mineral based, once they are clogged then the bacterial growth is limited. For aggressive nutrient reduction the bacteria has to be able to grow in population so therefore it does make sense to change out the rocks on the set schedule.

I just suck at sticking to my schedule because I have to completely lay the reactor on its side to get the pump chamber out of the reactor as it is literally shoehorned into my sump under my tank stand.

There was a horizontal reactor released to market about a year ago that I was really keen to try because it would be a HUGE improvement in ease of access for me but the cost is a bit prohibitive so I never quite connected to the idea.