Author: Aqua Gardening

Aquaponics Backup Aeration System 12 Volt

An important part of an aquaponics system is to have a backup aeration system to keep your fish alive in the event of a power outage. Fish need aerated water and without it they will die in a matter of hours (depending on the amount of fish in your system).

A simple solution is to use a 12 Volt air pump, a Car Battery and an Automatic Switch. You can run the 12 Volt air pump off a car battery and use a 240 Volt car battery charger to keep the battery full of charge. In the event of a power outage, the Automatic Switch turns on the air pump. The air pump will continue to run uninterrupted off of the car battery until the mains power returns.

To build a backup air system you will need the following components:


Automatic Switch for DC Backup Systems

The Automatic Switch for DC Backup Systems is a device that will turn on your backup aeration system automatically, as soon as the mains power is lost. The backup switch can be used with any DC battery, and it can also power any DC device up to 15Amps and 32Volts or less.


12 Volt Air Pump

For large systems with a lot of fish we recommend a 12 Volt, 25 Watt air pump which pumps around 55L/min of air and draws around 2 Amps of power from a 12 Volt battery. We have a range of 12V DC Air Pumps available in our online store.



12 Volt Battery

You can use almost any 12 Volt battery to run the above air pump but it depends on how long you want the aeration system to run for in the event of a power outage. A 12 Volt car battery is the cheapest option however they do not have a huge amount of amp hours and will only run an air pump for a few hours. Also once a car battery has been completely discharged, it will never recover to its full charge capacity.

The best backup battery to use is a deep cycle battery. Deep cycle batteries have a larger capacity than car batteries and don't mind being fully discharged in the event of a power outage.

The following 100Ah Deep Cycle Century battery is a very good option. The 100Ah rating stands for amp hours. The 12Volt air pump draws 2 Amps per hour and so it would run for approximately 50 hours off of a 100Ah battery. That gives the fish 2 entire days of air supply, plenty of time for the power to be reconnected.

Deep Cycle

100Ah Deep Cycle Battery

Price: $170 - $250

Available from any good battery shop, camping store or car parts supplier.

12 Volt Battery Charger

The final component is a 12Volt battery charger. You need to make sure that the current rating of the charger is higher than 2 Amps, since this is what the air pump draws. That way your battery will always stay fully charged.

12Volt Battery Charger 2.5 - 4 Amp

Price:  $50 - $80

Available from any car parts supplier.

The above backup system is simple and only needs a single air pump. You can use your household battery charger and any old car battery that you have lying around to get the backup system started.