Where to place osmolator 3155 sensors in a sumpless tank?

[Mightyfish]

Hi Roger, first of all thank you so much for assisting many of my questions in regards to various Tunze products. I only have started marine a few months ago and have bought 9 of your products and hence so many questions.

I recently set up a second tank which is sumpless and open top rimless tank. I bought another 3155 for topping up water but i am confused about where to place the operating and optical sensors. I have both sensors hooked up in the large magnet and set The distance between normal water level and safety shut off at 20mm switching distance. Since this tank is small so i fill water up as high as possible and normally it is up to 2cm from the rim of tank. My questions are:
1. Is 20mm switching distance the way to go for my set up?
2. Where is the safest position to place optical and operating sensors without flooding my tank should water get filled pass optical sensor?
3. How does this operating sensor work? I.e. does it stop only if water push the operating sensor float until it hits all the way to the top of the sensor unit?

 

[rvitko]

Thank you for choosing our products, I am happy to help.

The optic sensor is the real switching sensor and the float is just an emergency back up that shuts it off if the optic sensor fails. I would place them as close as possible in general. The optic sensor will turn on the pump when water drops past the point where the cone transitions to a cylinder, the optic sensor will shut off the pump when the water reaches the point where the cone becomes a cylinder. Their are also so timers involved, the controller waits until it detects a low level for 5 seconds before filling, the green light will blink during this time. The controller also deliberately overfills for 10 seconds to avoid constant cycling on and off for every small change. If the tank is smaller than 40 gallons, I would open the controller and turn down the pump speed (red knob in lower right of board labeled min/max) this will make sure less water is added in the 10 seconds and the fill will be slower. In the smallest tanks it may be necessary to set the float and optic sensor further apart to account for this overfill.

 

[Mightyfish]

To keep both sensors furthest apart did you mean to set switching distance at 29mm instead of 20mm?

 

[rvitko]

Yes, or somewhere in between as needed.