UPS - a requirement for your tank?

With winter approaching, now may be a good time to consider whether a UPS - Uninterruptible Power Supply - would be helpful.
A UPS is essentially a large battery which will keep electrical things running in a power cut. How long it will keep them running depends on;
1. the watts the appliance uses
2. the size of the UPS.
UPSs are designed to handle a large load for a short period of time rather than a small load for a long period of time but they can be useful on a tank. For instance our computer has a UPS which will, in the event of a power cut, keep the computer running for approximately 5 minutes. This will give us time to save our work and shut the computer down properly without losing, or corrupting, data.
A reasonably sized UPS should run your aquarium filters for several hours. A heaterstat uses too many watts though so unless you buy a very expensive UPS, save it for the filtration.
When the power goes off, the tank will keep its heat for a reasonable length of time. The fish will cope with a slow drop in temperature over several hours, it is sudden temperature changes which upset them. You can cover the tank with blankets or polystyrene to help keep the heat in but once the filters stop, the bacteria can start dying very quickly.
You must have a filter able to restart on its own without needing to be primed. We have tried a UPS on both Fluvals and Eheims and discovered the Eheim coped well but the Fluval wouldn’t keep going. Something to do with the motor design and the fact that the power from the UPS is not an exact replica of true mains voltage, which is a sinewave shape.
There are UPS’s that do output a true sinewave shaped voltage, but they are considerably more expensive.
If you live in an area prone to power cuts, a UPS may be worth considering. They can be bought from computer or electrical appliance stores. The cost of one which will keep your filters running starts at around $160 and goes up.

- Caryl Simpson
Marlborough Aquarium Club