After reading Sanjay's article, I think I'll just build my own. It was very informative. Why can't I just build it out of PVC tubing?? I want to make it 4" PVC, and have a threaded cap on the top that I can easily remove and teflon tape again. How often do they need to be serviced?? Just to replace the media right?? The design seems pretty simple, kind of like a DIY skimmer where you want max contact time with the media (aragonite, bubbles, etc.). BTW, I have a pinpoint monitor which I assume will be helpful when getting the effluent flow rate right. Thanks for your help and info.
Stupid newbie question: What stops bacteria from growing on the aragonite and making the reactor a fluidized bed filter?? Is it because the aragonite is dissolving and preventing the bacteria from attaching??