Water level sensors from China

[Bomber county wanderers]

I ordered some of these WS-03 "no drill" proximity sensors from China a while ago as the plan is to attach three to my water tank and have a push button and 3 leds to show the water level. As usual they came with no instructions other than a basic schematic. On each sensor there are 3 wires Red (+ve 5-24v), black (-ve), yellow (signal 300mA). Am I right in thinking I can just connect an LED between the signal wire and ground or is there more to it than that. Do I need a current limiting resistor in series with the LED (or just use "off the shelf" 12v ready ones). They took a month to come some I don't want to fry one experimenting.

 

[hilldweller]

A 12V LED and oft you go. The output could work one of two ways, LED to +12 or LED to ground/0V.
If it were mine I would try LED to +12V and to output on the basis current sinking is the easy interface to build in.

 

[Bomber county wanderers]

Sorted it, 12v LED between signal and +ve gives a "light on" and LED between signal and -ve gives a "light off". I'm going to go with the former so 3 lights illuminated to indicate a full tank and put an on/off switch in the feed so its not annoying at night.