Top-up System With Low Voltage Solenoid

It is possible for any solenoid valve to become blocked by a foreign body from the water supply so that it will not close fully and may still pass water. In order to prevent this occurring it is important that a number of safety systems are put in place as a back up should this occur.

 

We have shown two methods of operation for the low voltage solenoid valve and have described both systems.

 

The first method is to use the solenoid valve to control water flow from a reservoir, which is positioned above the tank or sump so that it will naturally siphon out and into the tank/sump. In the case of a solenoid valve or float switch blockage with this installation, the volume of fresh water entering the aquarium is limited by the reservoir volume. (See section on recommended timer backup if reservoir volume is large enough to cause a dangerous salinity drop)

 

The second method is to connect the solenoid and top up system directly to an R.O. unit to allow continuous replenishment. The volume of water that a mains supply R.O. unit can produce is infinite and therefore potentially disastrous to the aquarium. We would therefore always recommend that the there are at least three safety cut off devices operating on the system. These are:-

 

 

 

To use the timer in this way it is necessary to first determine the duration that the RO unit takes to replenish the evaporative loss from one 24-hour period. Mark the position of the water level at its normal running depth in the sump or aquarium and then leave for a period of 24 hours without adding any more top-up water. Set the top up system running and measure the time taken to refill back to the mark.

 

With this information, the timer can now be set to just longer than the required time for full top up. If the float switch or level controller now fails, the timer will still switch off the fresh water supply and the aquarium will not become flooded. Be aware that his fill time may vary seasonally with evaporation rate.