Just to add the bubbles create water column mixing by pulling water up with them and surface agitation which is why its a good option but not the only option… waterfalls, fluming, fans and eace makers also can work.
Its not the bubbles but the action of the bubbles that aerate the water and why matching pumps to proper airstones is the key not by gph of the pump to the volume of water as many seem to have some formula for
As @Ponky said exposure or dwell time and suface area are
Hey, I appreciate your input! Soo, to start, I’m filling my sites from the bottom all from the same fill manifold/ 1 pump which takes about 15 minutes to start overflowing. At this point I get a waterfall effect in my res. I also run a circ. Pump that makes my res very turbulent 24/7.. what you think?Depends on your delivery of water… its surface agitation thats key and where the gas exchange happens. Contrary to what most think it is NOT the bubbles but rather the surface agitation they create…. Can get more depth if you feel the need.
If your delivery or input is above the water level and it causes good surface agitation and water column mixing then absolutely no need.
On the contrary if its below and does not agitate the surface well you can do individual and possibly just the supply depending on how its setup.
If you can break out the crayons and give me a half assed look at the flow directions, pump rating and supply res are like i can give you a better idea.
Ideally your pump and return lines should be able to turnover the actual volume of water that your grow sites hold at a min 4x per hr and 10 would be a good place.
Hiw many sites on a loop matter so if you are feeding to each site individually from the res (done many way) then your in a good place for an easy answers