One thing that I haven't seen discussed is whether these provide any of the other benefits of a refugium. When you harvest your cheato, do you see a lot of pods?
Tristan has been very clear and very upfront about the ARID Reactors purpose while speaking over the phone and via email....
The ARID is NOT a refugium by design. It's sole purpose is to reduce and remove phosphate (PO4) and nitrate (NO3). It's so good at this, many folks actually need to add NO3 to their tanks, and I went from PO4 levels that were too high to PO4 levels that were too low and losing corals because of it until I got it dialed in.
The ARID is a nutrient export device and that is it's sole purpose. Pods and the like may grow/live/breed in the ARID, but that is a side benefit.
When I ran an algae based refugium, I had many many more pods in it and in the DT, but I did not have anywhere near the PO4 control and was still needing to do alot of weekly water changes and run alot of GFO to keep PO4 at the upper end of tolerable levels.
If you want more pods etc, run a fuge for them. If you want to destroy PO4, get an ARID.
It is actually possible to run an ARID and have a smallish rubble area in your sump (or in the DT if desired) to increase your pod population.