From the Hurlcon VX9T SWG manual:
Your VX Chlorinator incorporates a run dry safety cut out. When the Chlorinator turns the filter pump on, it will check for water flow. If no water flow is detected within 3 minutes, the chlorinator will turn the pump off. This is designed to protect the pump seal and parts from overheating if no water flow is present.
Also
[quote:1nbo4gqg]Apart from messages displayed on the User display, there are two warning indicators.
(a) LOW SALT: This indicates that the concentration of salt has reduced within you pool. To rectify, add salt
at approx. 50kg per 50000 litres of water (see 3.5 Salt level below)
(b)
NO FLOW: This indicates that the Chlorinator thinks that there is
no flow to the cells. Potential
problems/solutions are described in the Diagnostics section.