Trying to simplify the design a bit... a smaller nutrient container will be beneficial with small dosages.
Currently searching for a different design check valve. The ones we commonly use have two rubber lips and need a little bit of cracking pressure to get the flow started. There is a different design with a movable flap or cylinder that covers up a hole in one direction, and allows flow in the other direction. That design has almost zero cracking pressure, that is, allows fairly free flow as soon as the pressure is zero. That would be optimal and might even alleviate the need for my super latex glove solenoid.