OpenSprinkler Forums Hardware Questions OpenSprinkler Pi (OSPi) Fertigation Usability

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    Hi, I’ve been looking at the Open sprinkler system and I’ve been wondering if it’s possible to modify it in order to apply  it to a fertigation system for a small farm.

    I’ve been looking at trying to build a DIY system and I’m looking for something flexible that I can use to avoid paying the cost of a new system. ( which can be upwards of around about $7000. )

    To work, the system need to be able to control 2 solenoid valves based on the input of an EC sensor, with a manual override. As well as 2 pumps and Solenoids at the outflow point to control which bay to water. Any help would be greatly appreciated.

    I’ll draw up a diagram in paint, forgive me for the roughness but I’m not very good at it. As long as I can get the point across I suppose.

    Fertigation System

    So the system works with Venturi Injectors which have no moving parts and use physics to inject the fertilizer into the mainline. The amount of fertilizer is controlled by using the solenoids which turn off and on depending on how much EC the sensor is reading. The reason for manual override is when using bore water, the EC sensor cannot read it and so the control of the Fertilizer control solenoids needs to be controlled manually/hard coded. The rates can be worked out since the Venturi injectors are rated.



    If I understand this correctly, your bay 1 & 2 solenoids can be operated by schedule with OpenSprinkler (they are just valves or ‘zones’).  Pumps A & B, no problem.  There are provisions to provide pumps with power when zones are on.  You have 2 pumps instead of the standard 1, but that could be worked out easy (Especially if don’t you need them to work independently).  Ok – A & B Solenoid controlled by an EC Sensor – home irrigation control just doesn’t have anything like this.  More info is needed.  How does the EC sensor send information, and can that be mapped?  My guess is yes, you’d just need the specification of values that it sends, then build the logic to open/close depending on that info.  It isn’t clear if you need A&B to open fully or need to open on a range of values – I’m sure there are valves that do this, but the ones used in home irrigation are just opened or closed (or if you’re unlucky, stuck open by a grain of crap and you come home to a flooded yard).

    But my guess is there is something more complicated here.  If you are saying the standard system sells for 7k, and the only part of it that is complicated is that EC sensor, then what is driving the price up?  Maybe liability considering we are talking commercial farms and fertilizer?  Sometimes simple is better – I wish you luck!



    Thanks Mark for the clarification. I’ll do my best to explain the some of the queries you have.

    I am still designing the system myself, so none of it is actually working yet. The system I designed above is an example of the system that is set up at another farm. To be completely honest with you, I’m just trying to design a system that works, and is simple to work out and build. The reason I’m posting here, is so that I can determine if Open sprinkler is capable of doing what I need it to do.

    The second pump is not exactly needed, like I said I am just copying the system I examined. There was another one I saw that used 3 pumps in a slightly different set up. I don’t think those would be a problem anyway because in every system I saw all of those pumps turn on at the same time just like you guessed.

    Concerning the technical specifications of the EC sensor, I am unsure exactly what they are, but I am confident that they can be mapped. The EC senses Electrical Conductivity, and is generally used to measure how much food is in the water. For farming, the values should be at around about 2-4 depending on the weather.

    Whether or not I need the valves to open at a range depends on if it’s possible to manipulate the amount of liquid going through the valves in other ways. In my mind, I was thinking of using on/off valves, and then adjusting the amount of time they would be open (say 3 second intervals) to control the amount injected into the mainline. It could probably be done with adjustable valves but I think that is driving complexity higher.

    To me it seems like it’s very complicated and that there is more going on, but as I’ve been researching it, it seems to be quite simple. Standard systems sell for upwards of 7k depending on how much of the system you want to automate. I’m looking for something I can build myself, so I know how to fix it if anything goes wrong, and won’t be to expensive either.

    The only other thing I noticed from the other systems I examined was having a percentage based balance system for A&B. I thought it would be a bit of trouble to get it working on top of everything else but I don’t think it’s too important. Basically controlling a ratio A:B to inject into the mainline.

    Like you say, keeping it simple is what I’m aiming for, and it’s looking like opensprinkler fits the job quite nicely.



    I will make some high-level comments: in general if you are looking to build a custom system, OpenSprinkler would be a pretty suitable platform, due to its open-source nature and the availability of spare pins which you can use to extend the hardware functionality. A while back I modified an OpenSprinkler to become a biology experiment controller:
    it controls two linear actuators, two solid state relays, one air valve and it monitors CO2 level using a CO2 sensor.

    The existing OpenSprinkler firmware can probably cover most of your need already. You will likely have to change the code to support EC sensor. Because OpenSprinkler is based on the Arduino software platform, if you have any sensor in mind, you can just Google ‘EC sensor Arduino’ and you should find some links with useful information, perhaps even with an Arduino library or source code you can make use of directly.

    This is just my high-level comments. I did take a quick look at your description of the system, and I am pretty sure it can all be done. The question is how much hardware and software changes it involves, hopefully not much.



    Did anybody program the code for this already? I need something like this for a greenhouse experiment with different kinds of fertilizers. I should be able to dilute the right ec/pH from concentrated solutions etc. I think a Raspberry Pi might be a nice solution to build something?

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OpenSprinkler Forums Hardware Questions OpenSprinkler Pi (OSPi) Fertigation Usability