I'm a tinkerer from way back, and I wanted to reverse engineer an Undercurrent system, and add a few tweaks.
Mine is based on 5 gallon buckets- I know, a bit small for some people's taste, but the price was right- FREE!- and I use 1" bulkheads, from ngw. Don't use the CAP ones, they leak. 1" inside diameter hose connects all the buckets together, and I use 3/4" hose from the pump in the tail bucket- this being the main difference between my RDWC and UC- to the head bucket, aka 'epicenter'. So, water flows from my head bucket out several hoses to between two and four rows of 5 gallon buckets, between 12 and 24 in all, and then the hoses connect with the tail bucket, where the pump is. Res. float valve fits into head bucket, as does cooling coil from chiller.
In this way, I can pour water, undiluted nutes, H2O2, or whatever into the tail bucket and it gets mixed/diluted twice before ever entering a growing site. Also, I experimented with a pump switch but found that things ran better continuously.
I get ease of operation, long nutrient life between changeouts, massive growth, and as long as all the parameters are under control, no problems with pathogens. Oh, and did I mention it was a cheap build? I spent less than $300 for a 24 site system, not including chiller.
Not everyone likes to run airstones, but I put one in every bucket. For a 12 site system I use an EcoPlus Eco 5 airpump, 110 liters/minute. For a 24 site system, I run the EcoPlus Eco 7 airpump, 200 liters/minute.
I have and am still learning how to properly use a 30 site ezcloner- slime problems- and I use flood n drain tables for rooted youngsters.