Anyone have success using a water pressure gauge or sensor that will give a pressure value on ST? Have a well pump that is controlled by manual timer but when leave town and sprinklers run pressure drops. If no one is home to set the timer I have no sprinklers. I have seen multiple contacts that i can turn on the pumps as needed but need to know what pressure it is to start it. I don’t even need a pressure reading a normally open or closed switch based on pressure that a device would recognize the voltage or loss of that can control the pump as well. I contacted ST support they said talk to the community.
@tljensen try searching pool, Arduino, pressure sensor. There was a topic with some guys that’s made one with Arduino for a pool. If you’re not an Arduino guy this probably won’t help you. I’m not one of those guys either.
I reached out to them today wondering what they offered waiting for an answer thanks!
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are you using an Arduino board?
Well, probably a bit late from the original question and a bit unrelated, back in August last year, but here I go:
(note; due to “smartThings new user restriction”, I’m only allowed to publish one picture as part of this text). So I had to cut down quite a bit and chose only one representative. Tough decision to make, but I have save the original post and will publish it on my own private blog server with no restrictions!)
Due to extensive international business travel, I had the same issue; monitor my swimming pool filter in order to call my pool maintenance techs when the pressure was becoming too low (or too high).
First of, let me say that there is a sensor device already available at https://phoenixsensors.com/products/wireless-pressure-sensors/ but only operates on BlueTooth, and connect to an app on your phone under a proprietary communication protocol. This was a good start, but first very limiting in my end goal, and second outside my budget.
So this was a no-go. Instead, here’s my personal (and preferred) solution:
SENSOR
For the pressure sensor, I used a cheap yet extremely reliable sensor:
DIGITEN G1/4" inch 5V 0-1.2 MPa Pressure Transducer Sensor Oil Fuel Diesel Gas Water Air.
At 15PSI average, I’m not using the full scale of the sensor, but the reading is pretty accurate I have to say.
I used a T shape coper adaptor to keep the original gauge in place. Always good to have both.
GATEWAY
For the gateway, I chose the Photon from Particle.io
Excellent affordable (20 USD) Arduino based platform with integrated Wifi, battery management, SDK, full API cloud connectivity on Particle’s cloud, etc…
check http://particle.io for more details, but I highly recommend this solution.
Originally, I had used the Electron (3G based unit), but it’s cost of operations are prohibitive ($3/month for the first MB of data, that’s $33/year, no way!. This can be a solution if no WiFi AP is available though.
To connect with the I/O and other peripherals, I’m using a shield for another 20USD, but a custom PCB could definitely save some costs here.
For WiFi connectivity, I’m using an external antenna. The on-board Antenna is too small and can’t connect when the pool filter is too far away from the access point as it is in my case.
There is more to the design; one important aspect is power and that’s the tricky part I’m still working on. For now, I use a regular 5v USB charger, but I’m working on having a solar panel solution so it can be 100% autonomous.
BACKEND
For the backend, I’m hosting all the services on Amazon Web Services (AWS). Collect the data via pubnub.com, then publish them on a custom dashboard from thingspeak.com.
Here are some exemples of what I can do with it:
_(NOTE: Please don’t mind the temperature reading (50C). This is full sun exposure on a hot summer in Arizona, and middle of the day during the current reading!!!)
ALARM
The Real motivation behind this project!!!
I have set some triggers on AWS, so to text and e-mail me when something goes wrong, mainly when the PSI reading is outside the range. A text (and e-mail) is sent to me and to my technician directly so I don’t have to explain what I’m seeing 
COST
Total cost: $100 for a proto, but I’m sure we can squeeze it down to $50 fairly easily. There are some recurring costs around the cloud infrastructure based on the usage, but that’s minimal compared to what a new pool equipment would cost.
On top fo that, there are lots of custom-modification I can make, such as automatically assert the pool schedule time based on external parameters (ambiant temperature for instance). I am planning to add a PH Sensor reador also and connect my gateway to the salt-system generator and monitor other parameters that way. (I have yet to figure out how to use the aqualink and I would welcome any relevant information)
CONCLUSION
This is a very high level of the whole solution, but there are quite a bit of SW development around all of that which I’m planning to push on Github when I’m done with some live examples (i.e. live gauge readings from thingspeak ) so you can witness with your own eyes.
Sky is the limit here with all the different application we can come up with such “simple” and cost effective solution.
Did you ever complete this project? If so, can you share the code?
I completed it, I didn’t use an arduino board to do it. I installed a normally open pressure switch on my water line, when pressure drops it closes the contact. I used a Fortrezz Mimolite to see the closure. Mimolite has a dry contact relay in it that can be turned on and off by smartthings. I used a transformer and 24volt coil relay to step down power from 208 to 24 volt (pump start/stop on manual timer). I connected 24V through the mimolite dry contact to coil of other relay. I have no code, i used rule machine to set it up when pressure switch has pressure drop, mimo will see voltage change, i delay it for 30 sec, close the mimo dry relay to turn on pump. After water pressure increases and open mimo detects it, I set a 45 min delay to shut pump off after 45 min to fill large storage tank.
It has worked flawlessly for a year. I send a notification of every step, so I can monitor the process as soon as pressure drops to make sure pump does turn back off.