Water sensor switch?

[jschall]

I want a water sensor switch that will close a solenoid valve if my DIY siphon overflow fails and my tank starts overflowing. Are these available commercially or will I have to DIY?

I want to use a water sensor, not a float switch. I think a float switch would be too sensitive to surface agitation and would "false alarm" too much.

I need maximum protection against overflow to be able to convince my parents to drill a hole in their wall.

 

[johnptc]

try www.mcmaster.com

 

[Aquarist Andy]

A float switch may still be acceptable, but you would need to electrically filter the output signal to remove the effects of the surface agitation.

For example, if the float switch uses low voltage, say 12 volts DC signal, then applying a RC filter (series resistor and capacitor in parallel) could be used as a signal delay - so the float switch signal only becomes active after it has been on and stable for a set length of time.

You would need to calculate the 'time constant' = 1/(Resistance x Capacitance) to work out the time delay.

If you're not sure what I've been going on about, try Googling the comments I've made above. GL.

 

[skynoch]

A float would be less sensitive than a water sensor and for the application you are talking about would the float would work great. Floats have some play inbetween the make and break point. You would need some serious agitation in your tank to cause this. You can also use a time delay with a float to compensate for the agitation if you have that much

 

[swede]

the float would use the same principle that is used in a toilet head. open it up and check it out. gives you the basic idea, and i'm sure by looking at that you could come up with a simple float idea for this DIY project