water level detection

[discussmith]

Wondering if those who use various water level detection controller would care to comment on what type (sonic,ir,pressure,float, ?? whatever else) and what made you choose that type. Also any ramifications for that choice.

 

[joopie]

I use ultrasonic, with one device i can control my auto top off, drain and fill levels. Ii like to see the actual level of my sump, not just a toggle of a float switch.

 

[discussmith]

How have you dealt with the jittery response typical with ultra sonics, or do you not have issue? Do you have any concern about if the sound has any affect on livestock?

 

[sleepydoc]

I played around with a sainsmart ultrasonic range sensor and found it to be pretty consistent and accurate, down to a few mm for the ranges I was looking at. Any sensor will have some issues like this, however.

The best way to deal with it (and what I did) is to build some hysteresis into the code. i.e. if you want to set a distance of 10 cm as your trigger distance, you can have it turn on at 11 cm and off at 9 cm. That prevents it from flipping on and off excessively.

You have to decide whether it has adequate resolution and signal-noise ratio for your application.

Another option for reducing the effect of noise is to use an averaging algorithm to minimize the effect of variations in either the actual distance of the object or the distance reported by the sensor.

 

[emerald crab]

My ATO uses 5 consecutive readings (2mm or more under the set value) consisting in 50 averaged samples each, to turn on the pump and 3 consecutive readings (again 50 averaged samples each) equal or higher the set value, to turn it off.

 

[jewlz]

I like the ultrasonic and pressure based ideas, but when I was building my controller, I was worried about corrosion and salt-spray affecting the sensord long-term. In the end, I figured that you can't beat the simplicity of the sealed magnetic-float reed switches. They're cheap, and the worst that can happen to them is that they need to be cleaned...

 

[iced98lx]

For me:

• Float Switches
  
  Fairly reliable if clean, cheap, easy to string several together. Easy to debounce/make smooth. Simple 2 wire hookup. Must be protected/cleaned regularly.​
• Pressure Sensor
  
  Accurate, not sensitive to waves/etc when impelmented well.
  More complicated hook up. Easy to run tubing to move electronics safely away from the water. Very infrequent cleaning/maintenance required. Can give actual level information vs binary on/off​
• Ultrasonic
  
  Accurate outside of jitter issues already discussed. More complicated to hook up and monitor. Can give actual level information vs binary on/off. No cleaning/maintenance required. Difficult to package and place over tank/sump in a way that protects from salt issues​
• "Liquid Tape" (https://www.adafruit.com/product/463)
  
  Accurate, more complicated to hook up and actual level information vs on/off. No cleaning required. Requires flat surface to mount. connector at the top requires extra effort to protect from salt (cover in plastidip/etc)
  but has cable to move sensitive electronics away from the water.​

I've played with the above and those are my personal opinions. As far as in tank monitoring the most common discussion is ATO and I use a pre-built avast ATO based on a pressure sensor. If I were to build another ATO myself I'd use an eTape backed up with float switches for extreme high/low.

 

[iced98lx]

Woops this is a pretty old thread that got bumped... might still be useful.

 

[thegasman2000]

Liquid tape looks awesome but pricey!