1 Regulator, 2 selonoids, 2 ph controllers, 2 Tanks

I want get a dual manifold and run 2 seloniods, needle valves, bubble counters running to 2 planted tanks. Both tanks will be controlled by the Digital Aquatics RK Elite's ph controllers. One tank is a 26 gallon bowfront and the other a 55 gallon. The co2 tank will be under the 55 gallon along with both selonoids attached to the regulator and there will be about 16-18' of co2 "cable distance" to the 26 gallon.

My question is not how to build this thing, but what problem could i run into? My reasoning while both selonoids are working set the bubble count on both tanks so that if each tank was seperate, the bubble count would that much like a non controlled system where the controller would be on most of the time supplying co2. Now i imagine as soon as one of these selonoids turns off, there would be an increase in pressure to the other needle valve. If this was not excessive, there would be an increase in co2 production until the desired ph was reached and the selonoid would turn off on the second tank.

Does any see a problem with this?? I would have to fine tune the bubble counts, but that's no big deal. Orlando at Green Leaves Aquarium would be building the custom manifold to do this if it would work in the real world. I just don't know how much of a pressure increase to expect when one of the selonoids is off, as well as one tank having a higher bubble per second count because of the size difference. Anyone have any experience or thoughts???

Stevie D