More on Passive Systems

This is the time of year (mid-October) when my mind tends to turn to system design. What should I do next year. I've had two pretty tame Summers since I've taken a vacation last Summer and this Summer I worked on a study of image-processing and the Shroud of Turin which I hope will be up on the Ohio Conference Shroud site by the end of December. That tends to mean that next Summer it's back in harness growing tomatoes. But I want to take some time and drive around and visit some folks and now that our youngest son has gone off to the Navy there's no-one to tend the hydroponics system when we're away.
"If anything can go wrong it will" is one formulation of Morphy's Law, so leaving a hydroponics system to its own devices when it depends on the electrical mains is a recipe for dead plants. So I've been thinking about passive systems. I've mentioned wick and float systems. One passive system I've mentioned only in passing is the Auto-Pot system which uses a clever little device known as a Smart-Valve. Jim Fah invented this gadget and you can read about it HERE.

Jim Fah's Smart Valve and the Auto-Pot System

The Smart-Valve is the "brains" of the Auto-Pot system. It consists of a couple of interconnected float valves that both limit the height of the nutrient fed to a plant and prevent new nutrient from being added until the level drops to a predetermined lower depth. This little trick nicely simulates the way plants experience nutrient in the real world of dirt growing. I used one of Jim's valves on the Deck System long ago in Summer One and it worked just fine. I chose to use NFT instead in the intervening years, but I've always had a soft spot in my heart for passive systems. So a week or so ago I bought two of Jim's latest valves and I'm going to test a mix of passive systems this coming year to see just how much difference it makes to the plant to simulate the real-world nutrient cycle.