By hourly rate, I mean how much your time is worth per hour hahah. Some of these things take hours a week in maintenance to be 'more efficient'. I was doing my top feed in Brisbane in summer with ridiculous temps in the garage (over 40 degrees celsius). I sit the res on the concrete outside the grow space but never had an issue, just change it once a week. No chiller, no bennies, just a res on the concrete pumping through feeder rings and back to the res. Cheap to setup, just use two pots, one filled with clay balls and some holes in the bottom sitting in another sealed pot with a hole drilled for the pipe back to the res. Fishtank pump for the feeder rings and thats it. I'm running RDWC now but tbh it's not that much faster (maybe a few days quicker in veg?) and needs a lot more dialling in. And yeah, the pot socks just keep roots out of the return pipe