How It Works
The functioning is very easy.
Inside the three fingers on the probe there are just as many temperature sensors, and tiny resistances.
The resistances are always stimulated, resulting in the sensor reading a high temperature, normally. When it is submerged in water, the water temperature decreases the finger’s and the system senses a lower temperature.
While the system works, it will read the cold temperature in the lowest finger, the Min, while sensing “hot” in the other two Max and Alarm.
When the sump water level lowers, the Min will go from a cold to a hot reading, and the system will signal the pump to start topping off with reverse osmosis water.
Topping off time must be between 25 seconds and 10 minutes, as the system will work for 25 seconds before taking a new reading of the Max. As soon it reads the cold temperature, the topping off process will end.
If for any reason the highest finger should become cold, symptom that the water level got too high, the system enters the alarm mode, stops the pump and starts ringing.
This is extremely important because it warns us of any issue that might be occurring in the sump. At the same time, if after 10 minutes the Max level hasn’t been reached, the system signals alarm and rings. For lazy people like me is an excellent control system, as I often forget to integrate top off water!
For example, the above level controller, Elos Osmocontroller II, still is an excellent controller, but it didn’t have the alarm signal, which caused me to arrive to the pump cavitation before noticing that sump water was over.
In the picture above, you can see the probe with the minimum, maximum and alarm indicators, the latter activating when the level reaches the last sensor. Min and Max with a blue LED indicator, green for Power and red for Alarm.
Top-off water volume
After telling you how it works, we’ll also tell you… to what extent.
The following pictures show, with the help of a ruler, the two levels Min and Max in the sump.
The minimum value we read shortly before the automatic top-off started was of 22.2 cm, obviously this depends on the position of your magnetic suction cup.
Maximum level measured after topping off was 23.7 cm.
We measured a gap of 1.5 cm, a level that can be considered little or big based on your sump situation and your tank size.
Let’s see some examples.
In my case, with my old sump shown in the picture below, after having removed the internal divider:
I have a sump surface of 42×65.5 cm, therefore every top off event brings in the tank 4 liters of water. Salinity variation, on my 400 l tank is equal to only 1%. If salinity at the maximum level is 35‰, at the minimum level would be 35.35‰: an extremely low difference which I don’t think would cause any disturbance.
If we had available a sump with the return pump isolated from the rest, like in the Vertex sump:
It would change the level at the return pump area only, 41×14 cm, in which case every top off event would involve 0.9 l, and a salinity variation of 0.2%. A truly undetectable difference!
