Interesting concept. I'm new to hydro but have been working towards trying to eliminate airstones from almost the get go. They clog and appear to be a weak link.
Years ago I came across an invention utilizing a venturi to clean ponds and large fish farm tanks. The theory was that most of the oxygen exchange took place at the surface and recirculating the water was much more effective than adding air to it. Now these applications had their surfaces exposed to sunlight/light whereas our res' are hopefully sealed so I don't know if the theory translates fully.
Basically what we did was place an airline bubbler at the bottom of the tank and attatch a tapered hood a few inches above it. Connected to the tapered hood was a straight pipe that extended to near the top of but still below the water level. The air bubbles would rise into the hood and mix with water and because the mixture was lighter would rise rapidly and violently to the surface. To me this had the similar effect as trying to hold a vinegar jug half filled with water at the bottom of the swimming pool, it floats and can't be done, it wants to rapidly ascent. The tapering of the hood catches the air bubbles and also acts as a venturi as pressure is created to draft a volume of air from the bottom of the tank to the top, creating a lot of recirulating.
I've adapted this idea to growing in an aeroponic setup. I have an 8 site preveg 36 gal tote that I eliminated the airstone from by using a red microsprayer mister shoved into the end of the airline. I then drilled a hole in a 1/2" pvc plug and threaded the plug into a T fitting. Attached the T fitting into a 4 way cross so I have the T fitting at the bottom, a straight sched 40 PVC pipe at the top and use elbows to make legs for the sides. This uses air bubbles to draw liquid from the bottom of the tote to the surface.
Results have been good, performance more reliable than airstones, but I don't have a vast history to compare it to. Careful if you are trying to be discrete as the bubbles now sound like a kettle on full boil.
I've also made a mother keeper using a recirculating pump that seems to be doing very well.
I use a 350 gph mag pump to run my DIY aeroponic misters (again the red ones). I use 13 misters in 1/2" pvc frame in an 18 gal tote. I use 30 L of solution and a T fitting coming off the pump. One side goes to the misters while the other side has a flow control valve attached to a special part.
The part is a sump of a Versatile sprayer (part # 40-34200). Its available from agricultural suppliers and has a number of different fitting sizes attached to it. It has 1/2" thread on top that I attatch my red mister with the airline in the plug, another fitting into the flow control valve, a fitting inside that I fill with a plug drilled out to give a 3/8 " stream of nutrient, and a large opening on the bottom to draft some volume using the pressure created by this venturi.
I need to get a DO measuring device but roots are white, vegetative regrowth on the mother is excellent and it fit what I was doing.
I am interested in any ideas that can improve growth while eliminating a potential flaw (airstones). Hope this helps some as this site is amazing. Its turning into a full time job just catching up on the great ideas members here have.
