Quote Originally Posted by bobmcj View Post
Being an automation engineer, I would like to automate the backwash and not have to worry about it.
OK, I'm grinning, big time.

You have two options, in automating pool gear:

1. You can use pool industry valving, controls, and actuators, in which case automation is the REASON why you'll have to worry about it.
2. You can use full industrial piping and controls, in which case your automation may well cost more than your pool does.

I've worked with large commercial pools for years, and I pretty much stopped trying to use automation -- of any kind more sophisticated than a time clock -- 20 years ago. Pools NEED to be observed with a Mark I eyeball, a Mark II olfactory sensor system, and a Mark III aural input device on a regular basis.

I could automate most of what I can tell by glancing at the pool, as I walk downwind of it, on the way to check and listen to the system. But to RELIABLY do so, and to gain input that provided 90% of the info and problem detection I gain from my walk by would require all of the following:

1. RPM sensing on the motor shaft
2. Vibration sensing on the motor
3. Digital read out of both influent (< atm) and effluent (> atm) pressures
4. Volt-amp digital read out
5. Digital flow rate read out
6. Smart analysis system that could detect cavitation, prime loss, low rate suction leaks, etc. from values detected in 1 - 5.
. . . and that's just to monitor the pump and flow!

You'd know better than I, but my guess such a system -- at 99% effective availability -- would cost over $5,000. But, I have my doubts you could get it for that: most of the people I've encountered trying write pool monitoring and control software, understand hardly anything about pools.

So, if you are pursuing this as a means to gain genuine efficiency, fugeddiboutit!

However, if you are a tinkerer at heart, and want to do this as a hobby, I'd recommend this site,
Swimming pool control with Linux as an example of what can be done.