Swimming Pool Chemist Robot

[pomprocker]

So I bought an above ground pool, and taking care of it is something that would be cool to automate.

Not cleaning it, but maintaining chemical balance.

I would need to have submerged chemical sensors:

http://www.troublefreepool.com/pool-school/pool_water_chemistry

FC - Free Chlorine - A sanitizer which keeps your pool water safe and free of germs. Chlorine must be constantly replenished.
pH - Acidity/Alkalinity - Needs to be kept in balance to prevent irritation and protect the pool equipment.
TA - Total Alkalinity - Appropriate levels help keep the pH in balance. High levels can cause pH to rise.
CH - Calcium Hardness - Appropriate levels help prevent plaster damage. High levels can cause calcium scaling.
CYA - Cyanuric Acid - Protects chlorine from sunlight and determines the required FC level.


Then based on the results of some math, I would need to dispense certain chemicals. Chemicals can come in either powder form or liquid form. Probably easier to dispense liquid form.

Any ideas?

[SmAsH]

well, with the chlorine you could have a scoop/servo that tips a certain amount in the pool every week or so...
the chemicals would be harder as you need finer amounts... any ideas on how to measure?
and what will you use to run it, microcontroller or pc?

[Joker94]

you could have an upside down bottl with a servo attached to a tap and when you need to add a liquid chemical you hit a button and the chemical would poor.

You would need to work out the flow rate and have a computer run an algorithm on how long to leave the tap open for. There for for this application you would need a computer interface.

What way had you originally thought of controlling the system.With a analouge timing circuit or a computer interface. If yoou go with computer which i hope youwill, it would be call to have a small sreen that showed what was happening and that sort of thing.

And I hope you like to code pomprocker as it may take a long time

[paulstreats]

Most public pools already have sensors that detect levels and pump chlorine in automatically. They usually run manual tests because the sensors cant always be trusted. A standard small pump usually pumps the chlorine into the pipes that come from the filters then goes back into the pool.

Im sure that there are also auto ph systems, but these are also backed up by manual tests (in the UK anyway...)

 What im trying to say is that its a worthy project, just dont rely 100% on the automatic systems.

[madchimp]

for measuring the chemicals to put in the pool, what about using PVC pipe to make kind of a giant syringe you could use threaded rod hooked to a stepper motor to drive it and a pair of check valves on the end so when it is sucking it pulls the chemical from the source then when it is pushed it delivers the chemicals to the pool this would allow very precise measurements. of course this is assuming that PVC can tolerate the chemicals you would have to check and possibly use other materials accordingly

[Metal Slug 2]

You can also get chlorine in tablet form.  imo, dispensing those would be the easiest method.

[Joker94]

tablets may not be a bad idea. but i guess they are more expensive tan the liquid due to manufacturing costs. But you never no do you

[SmAsH]

don't forget the powder form its what i use...
each form has its own advantages an disadvantages, find which one best suits you needs by making a list of the pros and cons...