Plumbing several DWC systems together?

Yes, it's called RDWC. Use the "search" button and reap the rewards of the internets.

Solved! Put at least 2- 3/4" bulkhead fittings on the bottom of each DWC tank. Then put a pvc pipe extending to the desired water level of the shallow bin ( the pipe is either glued or threaded via male threaded pipe adapter) originating from the bulkhead (one overflow bulkhead per bin) on the inside of the bin. Make sure these two overflow style bulkheads are close enough together so they may overflow into a a 5gallon bucket but preferably 20gallon rubbermaid brute pail situated underneath the bins. Support the bins above the auxiliary reservoir bucket/pail but not touching it.
Now align another bulkhead (1/2" at least) in each bin so a 1/2" pvc pipe will connect each bin so they will share a common water level. It will look like two 90 degree elbows are coming from each bin bottom and connecting to each other with a straight piece of pipe. No overflow is sent from these two bulkhead/90 degree connections. It is only done so that the bins will share a common water body.
Now use two small pumps with basket strainers to pump water into the overhead bins. The water overflows from the bin down the overflow pipe and into the auxiliary reservoir below. Two pumps are necessary in case one fails. Because the water bodies are connected , if one pump fails, both bins will still overflow into the reservoir underneath and constant water level ( and a whole bunch of aeration!) is achieved.
Simply use the level sensor of your choice to replace evaporate water in the auxiliary reservoir, preferably a 20 gallon rubbermaid brute pail. You could use a 5 gallon bucket underneath the two bins ( for an aux. res. ) just slow down the water flowing from the two pumps with a valve so that the overflow will not be so violent to cause nuisance short cycling of the auto top-off level sensor. This is exactly the method I use in my 2 side-by-side grow cabs.

Originally Posted by problemsolver

Solved! Put at least 2- 3/4" bulkhead fittings on the bottom of each DWC tank. Then put a pvc pipe extending to the desired water level of the shallow bin ( the pipe is either glued or threaded via male threaded pipe adapter) originating from the bulkhead (one overflow bulkhead per bin) on the inside of the bin. Make sure these two overflow style bulkheads are close enough together so they may overflow into a a 5gallon bucket but preferably 20gallon rubbermaid brute pail situated underneath the bins. Support the bins above the auxiliary reservoir bucket/pail but not touching it.
Now align another bulkhead (1/2" at least) in each bin so a 1/2" pvc pipe will connect each bin so they will share a common water level. It will look like two 90 degree elbows are coming from each bin bottom and connecting to each other with a straight piece of pipe. No overflow is sent from these two bulkhead/90 degree connections. It is only done so that the bins will share a common water body.
Now use two small pumps with basket strainers to pump water into the overhead bins. The water overflows from the bin down the overflow pipe and into the auxiliary reservoir below. Two pumps are necessary in case one fails. Because the water bodies are connected , if one pump fails, both bins will still overflow into the reservoir underneath and constant water level ( and a whole bunch of aeration!) is achieved.
Simply use the level sensor of your choice to replace evaporate water in the auxiliary reservoir, preferably a 20 gallon rubbermaid brute pail. You could use a 5 gallon bucket underneath the two bins ( for an aux. res. ) just slow down the water flowing from the two pumps with a valve so that the overflow will not be so violent to cause nuisance short cycling of the auto top-off level sensor. This is exactly the method I use in my 2 side-by-side grow cabs.

Very helpful my friend and I thank you! Also, if you have pictures that would be killer.

lol stoners..