So with all this gardening that I’ve been doing, and upgrading the woodshop, where am I in Aquaponics?
Well, the bluegill are still living in their aquarium. But I don’t have a completed fish shed, or much of a start on the greenhouse. And the Fresno heat is coming, so it is going to be difficult to work in the blistering summer. So I’m going to wait until late October to break ground on the aquaponics system. When the heat has died off, and I can work without melting into a puddle.
That’s also another reason why I want my aquaponics system indoors, in order to control the climate. I figure if I use a swamp cooler and solar panels to run it, I can keep summer temperatures in the mid-80’s, instead of the low hundreds! When temperatures get that high, plants start wilting, fish start succumbing to disease, and weeds get seriously out of control.
Ah. Control. That’s another thing… how am I going to control everything? Sometimes I really wish I had a swimming pool I could convert into an aquaponics system. Think of all that thermal inertia!
What I really need in my case is a system that watches water levels and quality, switches the filling and emptying of the grow beds, and keeps the inside temperatures level. Near freezing temperatures in the winter are a problem, as are boiling hot summer days. I also want updates that I can read on WIFI from a tablet or iPad, and SMS alerts to my cell phone for emergencies.
So for the last several months, I’ve been experimenting with Raspberry PI, Arduino, FPGAs, and with irrigation valves, to see if I can build a system that does what I want. But it just wasn’t right… I kept running into problems with input / output and the limits of the electronics that need to be connected to an array of relays to make it all work. I see where people in the Maker Culture have made their platforms do things in similar ways, but only after adding relay shields and other things.
It finally occurred to me that a solution already exists in factories and manufacturing plants. Instead of an Arduino connected to a bunch of relays, and hardened for a damp environment, I should instead use a programmable logic controller (PLC) that already has this functionality built in. So I’ve been looking at various PLCs to work with. Allen Bradley is the one primarily used in the USA, and Siemens PLCs are used in Europe. However, I like and trust Siemens… so I’m not sure what I’ll choose as yet.
I’ve also downloaded a PLC simulator, and have been refreshing my knowledge of ladder logic – which is pretty old and rusty.
I’ve also started creating a system schematic of how it is all supposed to work together. At this point, I’m thinking of using the Raspberry Pi to interface the PLC to a generated web page on my home network that I can use to update the system through my iPad. I’m still studying how to work that out.
But I have the summer to get it all figured out, because I’m breaking ground for the rest of the project in October, and I hope to have it finished by May of 2016!