too much flow in the system
 

Hello , I am a newbie at horticulture and very interested hydro gardening. Q: I am building the 11 plant set-up , I have a good external pump ,115v ,magnetic coupling impeller, unsure of the flow rate tho,1" inlet port 1/2" outlet, would over kill be possible, too much flow in the system? also does the system drain back thru the pump at the end of the cycle to drain the system completely or maintain some kind of level ? I am not clear on the watering cycle,soo much to read. Q. Thinking of building a chamber on the discharge side of the pump with an air stone inside to airate the flow during the watering cycle only , my concern is if I airate the resivoir it could possibly cause the pump to cavitate reducing pump flow and also to help reduce dissipation of nutrients with all the bubbling going on full time in the res. may also help maintain temperature . Any thoughts please...

You can't have to much bubbling in your system. And yes the water does have to drain back through the pump until the next watering cycle about every 20 minutes or so. An external pump could be a problem if it wouldn't let the water in the garden drain back to the reservoir every time.