Am I crazy?

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So... living in Australia with first world problems such as overheating pools with insufficient chlorine, I want to build a floating, solar powered pool sensor that measures PH, Free Chlorine, Phosphates and Salinity, Temperature. I then want the measurements sent to my phone so I can track them over time. I have no knowledge of electronics but have some time on my hands, access to the internet and prepared to learn. I came across this site and got a bit excited. Is Mysensors a good starting place? Am I crazy to think that I can do this? ...and if may be so bold to ask a 3rd questions to experts what is likely to be the main technical challenges I need to solve? All advice welcome.

hek

Having it floating in the pool may pose some problems as you would have to get it totally water tight.

PH/Chlorine sensors can be pretty bulky (at least the once I've seen).

http://www.ebay.com/itm/Analog-PH-Probe-Sensor-Shield-and-PH-Probe-Kit-For-Arduino-R3-Water-Detect-/331878772045?hash=item4d45842d4d:g:J2kAAOSwQupXW-HH

http://www.appropedia.org/Open-source_colorimeter

I would probably suggest you try to add these to to your return pipe to the filter. Where you also have power available.

scalz

Hi.

Welcome :)
Yes i think you're at the right place ;)
I have no device like this. Your main challenges will be handling your sensors of course (find the right parts etc..) but I'm sure community will help you to choose, but also if your device will be floating, it may need it to be waterproof, and resistant to chemicals and vapors (perhaps some resins etc will help).

scalz

@hek you've beaten me on this :)

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Thanks @hek and @scalz. An encouraging start. I'll let the forum know how I get on...

gregl

Hey @Birdy - Jump right in the deep end eh?!! ( pun intended )

I say this as a pool environment is particularly hard on electronics.... and creating a floating sensor, whilst i think is a great idea, will be very tricky to do.

Ive been automating my pool for several years now and i use mySensors to show me metrics ( pool temp, roof temp (solar heated), pH, pump runtimes and the ability to turn it on/off as needed...using Openhab ( and thus my phone ).
There is also a pump to add HCL to the pool periodically as needed
There is some more info and the code here:
https://github.com/mgf909/PoolController_mqtt

Its really quite cool and my friends well impressed ;-)

pH is really hard to do...ive never got it working 100% right....Its a PITA to calibrate the probe and you need to allow for temperature fluctuations.
I hope one day to have another crack at this as well as add ORP ( measure chlorine ) and pressure sensor to the filter to advise when to backwash etc.

I love the idea of a floating sensor..I think this would be quite feasable for measuring water temp, but not really for measureing ph/ORP as those sensors are super fragile, and as mentioned above, getting it waterproof is very difficult.
I once made an RGB LED pool light https://goo.gl/photos/AmFdVfunQVpmsbk18 to be submersed in my pool. Even though its encased in casting resin, water still got into it - i think around the cable...it always worked , but when i removed it ( sold the house ) i noticed some corrosion...

PS: I'm in Sydney....and mySensors is perfect for this project and the 200000 others you will get into!

exxamalte

I was actually going through the same thought process as you did, @Birdy: solar-powered floating sensors measuring all sorts of things in my pool.
I also looked at pH sensors to test water quality, but the recommended recalibration intervals ranged somewhere between a couple of weeks and before each use. Sounded a bit too complicated.

The pool sensor use-case I'm currently focusing on is measuring the level of remaining liquid chlorine in a barrel behind my pool connected to an automated chlorinator. I looked at various different options and settled on a waterproof ultrasonic sensor to be built into the top of the barrel. I'm planning to combine this with a waterproof temperature sensor hanging on a long leash in the pool.
The pool season has just started and I hope to get that all built before it ends. ;)

rvendrame

@gregl, what sensor did you use for PH? I bought these two some time ago, but didn't have time to build up the sensor yet.

PH:
https://www.dfrobot.com/index.php?route=product/product&search=analog+ph+meter&description=true&product_id=1025

ORP:
http://www.phidgets.com/products.php?product_id=3556

Temp:
https://www.sparkfun.com/products/11050

My original idea was to measure PH, ORP and Temp in a float sensor (perhaps powered by a li-ion 18650 battery, recharged by a solar panel on top).

I was concerning about how waterproof I could make the case, yes. But I struggled much earlier: These sensors consume a reasonable mA power when running, and switch them ON and OFF via digital pins didn't work well ( I think there is some trouble with the 5V step-up I was using, tried some variations but never got it working fine).

So I parked it for now and I'm looking forward for time available (and support) to re-start it.

Just to share my history, without happy end (yet).

gregl

@rvendrame
Stick with it.... My pool controller is the reason I very reason I originally got into Arduino, which led to Home Automation and ultimately MySensors... I've learned a lot in the process and the rewards are great!!

The pH sensor I have is one from IONODE. They do not appear to sell them anymore, but its designed to be installed into a 40mm PVC T-piece and built for constant usage.. Similar to the "Industrial" ones here http://www.cwc.com.au/cat/sensors-probes/ph/
The phidgets site also has a pH sensor which is designed for permanent install http://www.phidgets.com/products.php?category=36&product_id=3551_0

Not cheap though are they!! I think my ph sensor was about $140 AUD

I made my own temp sensor... I just bought a Stainless steel bolt ( about 30mm long ), put it in a lathe and bored out a 5.5mm hole from the bolt side deep enough to install a ds18b20 sensor and epoxied it in.

The pH probe you have is designed just to dip in the water., take a reading then put back in its box...I have one like it for testing. I guess you could use this type of sensor, by periodically filling a tank with fresh poolwater, take your readings, then drain the water back into the pool... a bunch of solenoid valves to allow the water to flow in/out should do the trick. Or some irrigation poly and some pumps if you don't want to mess with the pool plumbing.

Here are some pics, in one of them you can see the homemade temp sensor and the pH probe installed in the pipework. https://goo.gl/photos/benm5vkpxbZjHEAW7

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Thanks @gregl - appreciate the feedback. And good to know someone has already tried this with some success.

My theory behind the sensors is that in a chemical pool (as opposed to salt water pool) you already have continuously monitoring electronic sensors which then trigger the addition of chlorine or acid depending on the readings. So continuous monitoring of pool ORP and PH is possible with a chemigen unit. I now just want to take these sensor hook them up to an independent unit and use it to send readings for my salt water pool. Thinking about it further it probably makes sense to fix it to the side of the pool (near the skim box). Makes waterproofing less difficult and facilitates pool level (and evaporation) monitoring. Sensors appear to be the main issue. I will investigate this further. Thanks for the advice.

rvendrame

@gregl
Yes I realized that I purchased a 'wrong' PH sensor, after more investigations. The ORP I bought from phidgets should be okay (as it is graded 'industrial'). It is ready to be connected to a PVC T piece too, and also costed a lot BTW. The ds18b20 I have is the waterproof version already, so no worries on that too.

Do you think it worth I start with this cheap PH sensor just for 'piloting'? Will it last some months of constant usage at least? Or will it give up in few days?

And what about the power supply part? It appears you choose to install your sensors at pump house, right? Do you see too much trouble for battery+solar powered version floating on the thank?

Thanks for the good feedback!