$100 description copied from bulkreefsupply.
Auto Water Change Plus Auto Top Off
Change your reef tank's water automatically with AutoAqua's AWC system. AWC & ATO All-In-One. Water changes are one of the most time-consuming maintenance tasks with saltwater aquariums. There has been plenty of debate over how much water you should change and whether it should be weekly or bi-weekly, but no one argues against daily water changes. Changing 2% of your water every day will greatly increase your tanks stability and potential for longevity.
Includes pumps & tubing
Optical sensors = no moving parts
Secure tube holders
Siphon breaks
The simple system uses dual optical sensors, one for a high water level and another for a low water level. The high water level sensor acts as the ATO sensor, knowing when to refill your saltwater tank, from the freshwater reservoir. The top sensor also lets the AWC Touch controller know when to stop refilling the tank after a water change has occurred. The low water sensor acts as the minimum water level when a water change is in progress. During the water change, the output pump will pump water out of your tank our sump into a wastewater reservoir, or floor drain until the low water sensor is activated, telling the controller to turn on the input pump until the high water sensor is tripped, completing the water change and then reverting to a top off controller.
It is important to make sure the optical sensors are placed in the same chamber (usually the return chamber) where the water level will fluctuate during a water change.
Specifications:
DC Pump Max Head - 6.5 feet
Flow Rate - 74GPH
Optical Sensor In-Tank Thickness - 0.53"
Optical Sensor Diameter - 0.78"
Magnet Thickness - 0.25"
Max Tank Thickness - 0.5"
Controller Dimensions - 3.75" H x 0.6" W x 2.25" L
Sensor Cable Length - 10 feet
Pump Cable Length - 6 feet