I use preset irrigation drippers (not variable) to calculate my flow rates. I measured these extensively over a long period and found them scarily accurate & precise. I have my main line on the ground which branches up to the drippers so no air pockets or siphon to complicate flow and reliability. Mostly I use 4 LPH drippers, if I need higher rate for one tank/rack I add another dripper. Do have your drippers above water level so you can visually check easily, especially if you have a large number of drippers.
I used to use timers and higher water pressure and jets but these add to the complexity, cost, trouble shooting and mess when a high pressure line fails (especially if you are away or askeep for hours). Nowadays, I just drip 24/7 which is best if your incoming water quality fluctuates or is much colder. I have a 5 micron ceramic prefilter to reduce clogging of carbon. I reduce my mains pressure with the standard tap that was there. Just crack the tap open slightly. I have one high rate dripper much higher than the rest so I know the others have enough pressure.
One of my carbon filters is a used water softer unit (resin). It is about 1.3m high x 30cm wide cylinder and I have not changed carbon for 15 years. This supplies a 25 Ton system so lots of water going through. There are cartridges for standard filters that you can self pack or just make your own filter.
