Imagine having your home grown crop of Trout , Barramundi or Tilapia almost ready for harvest. You are already planning the family get-together when you will proudly serve that wonderful fish dinner.
Then, while you are at work there is a three hour power outage…the pumps stop…the aerator stops…and disaster….all your fish are dead.
The most important piece of equipment in your Aquaponics setup is your back-up aeration system. It is important like backing up your files on your PC. A backup routine or system doesn’t matter and seems unimportant until you have that first disaster…loosing those important documents or assignment on your laptop, or loosing all those ready-to-harvest fish.
After that kind of event backing up becomes a normal part of your everyday routine.
Fish need oxygen just like we do, and it will be very quickly used up if the pump and aerator are not operating. Without aeration taking place, in as little as 30 minutes fish can begin to suffer gill damage and not many minutes after that …death.
Most fish deaths that occur in Aquaponics systems because of nil or too little dissolved oxygen in the water. That is another discussion for another day, but the importance of an excellent aeration system cannot be overstated.
So, what kind of things can we do in our Aquaponics fish tank to make sure that the water is aerated.
There are several commonly employed techniques. No doubt there are countless variations to these methods, but listed here are the three main and most useful means of keeping the dissolved oxygen levels up.
UPS
UPS is short for Uninterrupted Power Supply. UPS units are commonly used in the computer industry. These devices are obtainable from computer outlets and vary in cost depending on the sophistication of their design and the electrical load they are intended to supply.
UPS..Uninterrupted Power Supply - Typical unit.
The business end of a UPS. There are several mains power outlets.
They work like this. The UPS is hooked up between the mains power supply and your pump and aerator. Mains power is funnelled through the UPS to supply to your pump and aerator. The UPS will attempt to supply consistent power to your appliances by topping up any voltage shortfall from its inbuilt battery. The DC electricity stored in the inbuilt battery, and drawn from the inbuilt battery, is converted to mains type electricity by an inbuilt “Inverter”
So, if the mains power goes down, or completely fails, the UPS will keep your mains power devices operating normally for a short period of time. Most UPS’s have an audible alarm to alert you to the fact that the mains power has diminished or dropped out altogether. This is a useful feature although it is of little value if you are at work or not within earshot.
The main disadvantage with using a UPS is that it will only keep a pump running for fifteen or twenty minutes at best. It will keep an aerator running for an hour or two because aerators as used in domestic systems typically draw less than 20 watts.
This time can be extended by purchasing a very large capacity UPS, or by having larger batteries wired into the circuit of the UPS. This can become a very expensive exercise.
Once you have the UPS unit hooked up, leave connected long enough to make sure the internal battery is fully charged then pull the plug out of the wall and see just how long the UPS will keep your equipment running.
Auto Switching AC/DC Air Pump.
There are a variety of these available through aquarium shops and on-line. They operate normally on mains power and have built into them a place where normal dry cell batteries such as torch batteries can be fitted. More sophisticated models have a larger rechargeable battery.
As the name suggests, when the mains power goes off the unit will automatically switch to battery and continue to run supplying air bubbles to the fish tank. These devices have been designed specifically for the aquarium industry and are just wonderful for home aquarium tanks. They generally do not deliver enough air for a larger home Aquaponics system unless you are prepared to invest in the largest capacity model available, and possibly, more than one of them.
AC-DC air pump. This unit delivers 9 cfm of air on mains operation and 6 cfm of air on inbuilt battery. It has 2 x air line outlets.
You get what you pay for with these devices, the ten dollar model from the on-line auction site is possibly not the wise way to go.
Purchase from a reputable source where you have a really good chance of getting after sales service. Give the device a good work out by running it on battery (switch off the mains power at the wall). You need to know just how long it will run on that battery/s
That is important information, don’t believe what it says on the instruction sheet or box. Do a real test. You need to know how long you have got if there is a mains power outage.
A Fail over Switch and battery backup DC system.
This type of backup system is the most versatile and able to supply aeration to your fish tank for extended periods of time. Because it is based on activating a 12 volt DC pump this system is also able to provide water movement in the fish tank. This is possibly the most efficient way to provide quality aeration over an extended period of time.
A complete system consists of a switching device, a battery, a battery charger and a 12 volt DC pump.
When the mains power is interrupted the Fail over Switch senses the loss of power and immediately switches on the battery power driven 12 volt DC pump.
The water being pumped from the bottom of the fish tank and is directed over the water surface. An exchange of oxygen and carbon dioxide takes place by the action of the surface water being disturbed vigorously. Oxygen is absorbed by the water and carbon dioxide is discharged into the atmosphere.
The action of the pump also moves the water around in the fish tank thereby ensuring good mixing of the body of water. The mixing action rapidly distributes newly absorbed oxygen throughout the fish tank.
When the mains power is restored, the 12 volt pump is automatically and instantly turned off. The battery charger is activated and the battery charged back up to full capacity in readiness for the next mains outage.
The battery used is typically a fairly low cost lead acid motor vehicle battery of around 40 AH capacity. This size battery will typically run the back up pump for 6 hours, which is normally sufficient to handle most mains power outages.
If you want more backup time then increase the capacity of the battery/s.
For the possibility of mains power outages beyond the capacity of your battery, it is prudent to purchase a small petrol driven gen set. These days they have become very inexpensive. A small 500 watt petrol driven gen set can be purchased on-line or at tool shops and similar places for around 100 to 150 dollars.
This all may sound like a lot of trouble, having battery backup, and further to that a small generator set, but believe me, you will regret not having it if you suffer a lengthy mains power failure.
Imagine, your fish are almost ready for harvest and you loose them all because there is no adequate back up system.
It is like paying insurance, you hope that you never have to make a claim.
Murray Hallam
Backup equipment available Here.