UPS for tropical aquarium

[Jason Arthurs]

Due to our flakey local power supply I'm quite au fait with setting up UPS units for computers. However my wife is setting up a tropical aquarium and would like a similar level of protection for her fish.

Total equipment load is miniscule compared to computer equipment.

75W Heater 18W Flourescent tube 6W Filter pump 5W Air pump

----------------------

104W TOTAL

I'm assuming the power factor of the heater will be similar to an incandescent bulb i.e. approaching unity (1) but the pumps are presumably inductive mechanisms so would I be looking at 0.75 or worse? Flourescent tubes would normally have a PF of 0.85-0.9.

Ideally I'd like at least a couple of hours backup since we rarely have outages long than this, what sort of VA rating should I be looking for?

Regards, Jason.

[Jim Scott]

I lived in a rural area where electricity was dodgy. During power cuts I just chucked an old duvet over the tank. Cheap and never lost a fish.

[Andy Hall]

There may be a simpler solution, Jason.

From the size of the items you list, I guess that this is a relatively small aquarium?

First point is that a computer UPS is generally intended to give an output of however many VA (adequate to run the load) but only for a few minutes - long enough to shut the machine down. For example, if you go to APC's web site and plug 200VA for two hours into their calculator, it will suggest 750 and 1500VA units, but really only to get the run time. Cost £300.

If you look at what you have, you actually don't need the lighting during a power failure from the perspective of the fish. You certainly need filtration to keep running and if the aquarium is heavily stocked, air as well. With a lightly stocked aquarium, unless the air is used to run the filter, you wouldn't even need the air pump for a couple of hours.

Also, unless the aquarium is really small and the room cold, in a couple of hours, the water temperature is not going to fall very much (a degree or two perhaps), and you probably don't need to back up the heater.

So you could probably use a battery powered backup pump, turned on by a relay when the mains goes off and still be in pretty good shape. Alternatively, you could run the normal pumps from a pretty small and inexpensive UPS.

[Alan]

In message , Jason Arthurs wrote

A couple of hours without power for a tropical aquarium should not be problem.

[LSR]

Most fresh-water tropicals will survive a *gradual* temperature drop down to

60f or so (and a gradual rise back to 78f). It's sudden temperature changes that stress them. Marine fish are much more sensitive, but of course a marine tank would have sufficient thermal mass to barely notice a power cut of several hours.

-- LSR