Well despite the lack of proper automation (my controller is currently out of action while I fix the water level sensor problems), there has been good growth!

Unfortunately my plants have been showing some nutrient deficiency problems, such as yellowing of the leaves which I remedied by adding kelp extract, and tip burn which was a result of adding too much nutrient.

Some of the plants in the lower grow bed aren't doing so well though, and I suspect it has something to do with the water temperature (which is just room temperature, and room temperature's been very warm lately)

Also note the addition of a hose connector - this is to allow easy disassembly, and also allows us to hook up a garden hose to drain the water.

The hose connector has a valve in it as a fail-safe - if the pump activates while nothing is connected, the valve will block the water flow and prevent it from spraying everywhere!

While the controller is out of action, I've been having to manually initiate pump cycles for the upper bed, typically 2x a day. I can't automate it due to the salt-buildup problem mentioned in the previous post, because it makes the water level readings completely unreliable.

Next Steps

• Raspberry Pi Interface & PIC/ARM controller
• pH sensor integration (I have one verified that it works, but I need to electrically isolate it from the tank!)
• EC sensor (need to make one. physically it's simple - just two electrodes, but need to create a circuit for it and also keep it electrically isolated)
• New water level sensors that are resistant to salt build-up (I have an idea of how to remedy this)