differences that I see
Yes, I recognized the similarities, but why can a bio-rocker claim to reduce nitrates to zero when a wet/dry does not? Maybe a trickle tower is more like a bio-rocker?
One thing that is different between the trickle tower and the wet/dry is the depth of media, the koi club sites were pretty specific about needing more depth than I observe in the wet/dry filters in catalogs, and this was based on testing, as I recall. My notes say that minimum was 18 inches, I recall that some ponds used more. The minimum for the strawberry pot version was about 18 inches but the big ponds (over 1000 gallons, maybe 5,000) used 55 gallon drums (suspended over an indoor pond) or 5 foot tall PVC standing pipes (with 1200 gallons).
The trickle towers were also low flow. How does that compare to wet/dry filters? Maybe if the water exits too rapidly the nitrates just haven't had a chance to be processed. There was some data on transit times, but I don't have that. Maybe a bio-rocker works (I'm assuming that it does, of course, as advertised!) because it slows the transit time to make up for the short height.
Cell-pore makes cubes but I'll bet they would tend to crumble a bit. I saw some "professional substrat" or something like that by Eheim that is round balls of sintered glass. I suspect that this would be safer than lava, and the cubes, for situations where the pump was after (as in below the tank pumping up) rather than before (as we do in ponds where we are pumping to the top of a tower then flowing down).
Anyhow I find myself curious whether a deeper bed (18") of sintered glass balls in a wet/dry would take the nitrate out of an aquarium.
Not that I would do it, I know that my plants need those water changes.
anona, curiouser and curiouser