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PostPosted: Sep 3rd, '17, 01:35 
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Hi there!
TLDR: I want to design an aquaponics controller which is better/cheaper than the ones that I found online. I came here for some advice from the pros.

I was looking around and found no aquaponics controllers which know the following:
- Cheap (<200$)
- Can measure the power draw of the motors, and thus enabling redundant pumps ( basically you turn on the second motor if the first fails ).
- Can measure multiple ( > 10 ) water lever sensors which use AC not DC current to sense the levels, so they wouldn't degrade water quality.
- Can measure ph and water temperature.
- Connets to a wifi and has a nice interface from the web. Possibly connects to cloud so it can be monitored from far away, this can be fairly complex because of security.
- Is open source: all of the scematics and software are available with a good license, and made with open source software.
- It can control up to 8 power plugs with solid state relays ( 4 lamps, 2-2 air and water pumps for redundancy )
- It has a small touch screen display, so one doesn't have to deal with wifi if something goes wrong.
- Is user friendly enough to be used by a total noob so you won't have to program firmwares etc.. just to get it working. You just plug in the things, set it up and it works. Bringing down the level which needed to use such a system is important for me.

I think I have to experience to pull this off, having an electrical engineering degree + node/React/AWS(cloud) experience for web interface.

Questions:
1., From what I've heard water pumps occasionally die which cause the death of the fish in the aquarium. By measuring power and water levels the system could see if a motor fails and switch to other one. I haven't seen this in any system, why?
2., Is water conductivity measurements important in an aquaponics system? If so then I'd also add that to the pcb.
3., Is adding more water, managing ph and buffers autamatically important / should I automate these things too?
4., This pcb would include high voltage parts too ( the relays for switching motors ), but I would isolate them ofc. Is this something I should be worried about?
5., Should I add an output for a fish feeder?

I plan to make the prototype with a beagleBone black / raspberry Pi and then move to ESP32 since it would get down the costs by a huge margin.

My plan is to make a very very modest living out of this. I live in Eastern EU so I don't have high standards, but I have many ideas for sustainable agriculture / automation, and I would love to devote all my time to this. Of course the PCB would be open, but I plan to sell it if someone wants to support me when it is ready. Do you have a recommendation for a sales channel which would work with this community? Should I sell it on my own site?
I would also charge for the fully cloud option ( which I would have to pay for to be usable ) is this a good idea?
I progressed a lot already with the schematics but I would welcome any guidance / tips / needs!
Thanks!
VV


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PostPosted: Sep 3rd, '17, 14:06 
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There are a couple of threads about AP controllers here you may want to look at. Hopefully someone can point you to them.


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PostPosted: Sep 3rd, '17, 15:28 
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Measuring water flow would be better than motor power for picking a pump fault


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PostPosted: Sep 4th, '17, 00:19 
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Hey!
Thanks for the reply!
My point is cost effectiveness: Measuring motor current could be solved with 1-2$ and food grade water flow sensor is around 15$, which would be too much in the end. Plus I still have to measure the air flow too which would require different sensors.
I gave it a thought and I can't think of a situation where the power draw wouldn't drop ( broken pump ) or go much higher ( something in the tube ). Plus you would also see if your filters are used up since the power draw would go up. Am I wrong somewhere? Sure direct flow sensor is better, but I kind of aim for cost effectiveness, and I think it would catch 95% of the problems.
Thanks again!


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PostPosted: Jan 25th, '19, 18:47 
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Not a terribly recent thread but I’ll whack a few thoughts here for others to stumble upon later...

For pumps pumping there are 2 common methods industrially. One is current measurement, whack the power via a toroidal transformer, with a resistor, and ohms law gives you an indication of current without adding a potential point of failure.

The other method is a spring loaded flap switch, when the water flows it pushes the flap, if the pump stops the spring pulls it back. Eg: https://www.valvesonline.com.au/paddle-switch

I’d be looking at SDI-12 for environmental sensors it’s simple to work with and commonly used in water/environmental monitoring. I use it with industrial data loggers but there are adaptors available to use sci-12 with raspberry pi / Arduino / USB. The big benefit to SDI-12 is that it’s 3 wires (12vdc power, data and earth) and you can chain lots of sensors one after another. The logger/controller doesn’t need calibration as the sensors send back calibrated data when they’re interrogated.

Something old fashioned yet commonly done to measure water levels in industry is an airline and a small air pump. Pressure in the air line is directly proportional to the depth of the air outlet below the water surface. Using the aerator in aqua ponies to measure depth is logical, and will also give an indication of an aerator failure - the air pump could be monitored with a toroidal as well...


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