So I put in some work breaking down the Ebb & Grow controller I bought to reverse engineer. As I had suspected it has some proprietary electronics internally, so I decided to use the controller on a larger sized container as my goal was to build an ebb and grow system that would utilize larger plant sites. This way I can obtain a deeper flood and have a larger root mass. I will use the 10 gallon carlisle bronco trash cans that I have been growing in with peat based mix. This will require a pretty large capacity reservoir and it will need more gallons per minute of pumping capability. I noted their pumps have the intake on the bottom of the pump, this allows the system to drain to a lower level as the pump is responsible for returning the nutrients to the reservoir between flood cycles.
Here is an image of the inside of the controller "bucket" unmodified.
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As you can see there are three float switches on one side of the site.
Two switches are located down low and are used to detect level during the pump down (returning the nutrients to the reservoir). The system is in this mode most of the time, so adding water to a plant site between flood cycles would trigger the upper of those two float switches to activate the pump to return the added fluid to the reservoir. The lower of those two switches turns the pump off when the level has reached the low limit.
I am assuming the upper float switch is a backup switch to cause the system to pump down whenever the nutrients hit that high limit. The two floats that slide up and down on the plastic rods are responsible for the maximum flood depth. So during a flood cycle if the upper switch is activated by rising water level it will stop the pump and if the water drops low enough that the lower of those two switches drops the pump is activated to add more nutrients from the reservoir.
All in all it's a pretty slick setup. They definitely did not make it easy to break down, gluing the wires from all the float switches into the strain relief fitting took some patience to deal with and not damage the float switch wires.
I documented each switch one at a time as I disconnected them. This had to be done so I could take the float switches out of the holes in the controller bucket. It wasn't really required for the bobber style switches but I documented their connections anyway.
Here are a few images of my completed 10 gallon bucket controller. I still need to drill the holes to run 3/4" or 1" to the sites but that's all that remains other than drilling the lid for fittings to the reservoir. A few zip ties also for the float switch wires to tidy that up.
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I had to figure out how to mount the bobber float switches so I got creative with some stainless steel angle brackets and some carbon fiber rods of the right diameter (3/8"). It's very stable and actually works better than I thought it would.
I am figuring that I will run multiple pumps in parallel to move the larger volume of nutrients unless I can find a larger pump with the bottom feed design that also meets the requirements for growing.
For shits and giggles here is a shot of the controller logic board, the "brain" IC doesn't even have any markings.
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My biggest concern with the system is root clogs. Running the same buckets with the peat based mix I don't have a problem with roots getting down into the bottom bucket, if they do it's just a little and they don't try to clog the drain fitting. There is about a 3 inch air gap between the little bit of remaining nutrients and the bottom of the upper bucket with the plant.
I am considering running perlite as the medium unless someone can talk me into something else. Anyone have any thoughts on the matter? I just don't want to wash that much LECA. lol