I would like a "control panel" type gizmo for window cleaning.
Something you can ideally add to depending on what you wanted.
So you could have pump control for pumps one and two.
On and off switches
tds in and out, tds warning beeper over say 10ppm
LCD voltage gauges
Water level in tanks (if black)
Preset memory settings for higher jobs.
Things like that and more.
Us idiots window cleaners love to spend money well i do.
We have developed a panel controller for one of our Dutch distributors. There are products in development with similar features to those on your wish list. There is a product on the market with dual TDS the Liquid logic V2 This unit will also manage tank filling and TDS
On Off of the pump can be achieved with a radio remote, Either the factory fitted Ultimate units or the Stand alone retro fit remote
Also available as is a dual unit that can run two pumps independently. This Unit can be supplied with TDS.
Measuring water level in a tank is complex, The panel i mention uses an analogue float sensor however this can be effected by a range of outside influences for example the gradient of the road of even baffles in tanks.
We did also look at an ultrasonic sensor however background noise of passing traffic again can effect the accuracy.
The Controllers are an on one level very complex, yet deliberately designed to make daily use straight forward. Adding something to a control in the field is not as easy as it sounds as connections to the PCB would need to be made to allow for new hardware plus the control would then need the Firmware (program) integrating so it knows what it is reading and what to do with the information.
Some of what you are looking for there are units that will provide those features and in the future well who knows.