I have a reef aquarium which I need to protect against power outage. I've worked out that I would have to run devices totalling 300W to sustain life in the tank during an emergency.
Can someone suggest what would be the best solution to get me through a powercut. I would want something that would automatically switch over when the mains power fails & auto off when the mains power is resumed.
These power cuts always seem to happen when I'm at work.
Many thanks
.. Tony
Buy a computer ups and run the minimum necessary to sustain life off it, alternately get a ups and extend the battery capacity with a lorry battery and it will run for days.
mrcheerful
A computer UPS is designed to do such a task, but they are quite expensive.
I just had a quick look on ebuyer, and saw a 400w 650va for £65. I think that means it would run your 300w for just over 2 hours (650 / 300).
Another one, made by Trust is £27 for a 600va, but does not mention max output. It should do 300w though.
Bob
Get a standard computer backup UPS (Uninterruptible Power Supply) of the appropriate rating. Available from better computer outlets, but possibly not from your little corner PC shop.
Rick
I'm surprised at the power consumption, but a USP as suggested by mrcheerful is what you want.
What I've found in the many years I've been installing these things is that in-general, you get 15 minutes run-time on a standard unit at half-load, and it goes down to about 5 minutes at full-load. (it's reasonably linear at half load and less, so 30 minutes at quarter load) Thats for a standard unit - you can get extended run-time units though.
For a 300W load, you probably want something thats at least 1000VA, but you can probably arrange some non-critical things such as lights to not come off the UPS if you wanted to save some run-time.
These units are in the £500 region though.
You might also want to look for one that has user replacable batteries too, and look to changing them every X years. (Seems to be variable, I've seen some last over 5 years and still function fully, and also seen some fail after 18 months )-:
Gordon
No, it doesn't. 400W and 650VA are just two ways of indicating the maximum power output. One would need to look at the specs to find out for how long that could be delivered, in ideal conditions.
Beware used ones with knackered batteries.
There's a good guy over in uk.adverts.computer who sells reconditioned UPSs. You may have to Google a bit, or just post a question.
I think the first thing you have to do is decide the worst case time for which the system has to be supported. Say overnight, or about 8 hours?
Say that the standby power is supplied by a 12v lead-acid battery. At 100% efficiency 300W would be a battery current of 25 Amps. Over 8 hours that would require a battery capacity of 200 Ampere-Hours. 75% efficiency would raise that to about a 270 Ampere-Hour capacity.
So you would require a 12:240v 300W UPS and a seriously large lead-acid battery.
Not quite, unfortunately. The run-time is purely dependant on the battery capacity and load, and it becomes non-linear when the load is above 50% of the rated max. So a 400W unit run with a 300W load, I'd expect to last less than 10 minutes.
I had a 45 miute power cut here at the weekend - only one of my UPSs coped with it and then it really was on its last legs when the power came back!
Gordon
How large? Aren't average car batteries about 40AH?
Bob
Can you provide a low voltage backup system (heater, air pump, etc)? If so it's fairly easy to rig up a battery supply which is disconnected by a NC relay driven off the battery charger. If the mains fails the relay drops and activates the backup system. When the mains is restored the relay opens and the battery goes on charge.
Obviously you need enough battery capacity for the period you need to cover. E.g. 300w / 12v = 25A; 25A x 3hr = 75Ahr. That's quite a big battery!
You could arrange for an alarm system to ring you up at work or on your mobile if the power fails.
In message , Tony writes
300W sounds like a lot assuming that is basically the heating load- admittedly I've no idea how big the tank is :-)I wondering what other aquarium owners do and how long it will manage with no power?
What type of loads are you running? - some UPSs, especially cheaper ones, put out something not very close to a sinewave, and will not be suitable for controlling some types of loads, possibly induction motors (pump?), fluorescent lamps, and maybe phase-controlled thermostatic heaters.
Tony,
I have a 6' tank and have the same concerns. I *have* lost stock in the past following a power-out, when a pump didn't start up when the power came back on, so no oxygen was being added to the water. So, I bought a large (1800va) old double-conversion UPS second-hand from a guy who advertises on uk.adverts.computers (mentioned in another post also) called AndyW. Double conversion UPSs *do* put out a real sinewave, not the poor waveform of cheap UPSs.
Once fitted with new batteries it powered my essential stuff for about 4 hours. I decided lights, heaters, protien skimmer, wave maker and UV weren't essential, leaving just 2 filters and one air pump on the UPS. It would take ages for the water temperature to drop enough to be a problem.
Since then I've doubled the batteries in the unit (now 16x 7ah 12v gel-cells!) - it's huge and they all fit inside! The runtime is approaching
8 hours now - enough for most power cuts. However, I also have a small generator in the garage, so in the event of a long power cut I can use this to feed the UPS and top-up it's batteries.In power cuts in the last 3 years since this has been installed it's worked fine.
As the UPS is so big it is sited in a spare room, and I fitted a UPS outlet mains socket on the wall near the tank to feed essential equipment. I plan to move the UPS to the garage soon and use an armoured cable to carry it's output back to the house - another project!
Alan.
For some unknown value of /seriously/ large. :-)
I took an extreme linear straight line for the length of time needed to support the system, just to see if it is an ordinary 'few minutes' UPS battery.
It is more probable that the aquariun runs at some optimum temperature, that it has a minimum temperature to support life, and that it has a thermal inertia.
So it is possible that a few minutes of power cut is not going to matter, and during an extended power cut the full 300W is not required to be on all the time.
The UPS could possibly be cycled on and off depending on the temperature. This would reduce the Ampere-Hours required from the battery.
But the critical thing the OP has to decide before taking any other decisions is how long that aquarium has to be supported for, and at what minimum level.
Don't use a UPS.
Sort out 12V (or even better 24V) DC power to your aquarium. Pump should be easy, heating only slightly harder. Then build up a battery powered system, an on-line power supply to run this lot, a float charger to keep the battery pile happpy, and a relay to cut it all over.
300W sounds like an exccessive load though - I've seen _huge_ tanks that only needed < 100W for a few hours survival. How big is it ?If you chance across a UPS, then go for it. But I bet your pump hates it and just sits there making a buzzing noise.
Yes - typically...
BUT you need to work out what that 40HA is rated at - it's not 40 amps for an hour - more likely 20 amps for 2 hours, and if you tried to suck
40 amps out of it it won't last one hour - usually much less.There will be some small-print somewhere that will say something like "40AH at 10A" (Meaning that it'll last 4 hours if you only draw 10 amps out of it, but much less if you suck more.
Gordon
I have a reef aquarium also. Generally the issue is not maintaining temperature because in most cases you only need to run at a few degrees above ambient room termperature anyway.,
The main short term issue is maintaining oxygenation both for the livestock and also to keep the bacteria (used in different ways dependent on system) alive as well. For this case, doing something with DC pumping is perhaps possible, although pumps have to then be capable of coping with seawater. Generally, aquatic suppliers don't seem to have suitable DC pumps.
The secondary issue with some organisms in reef tanks is that they have symbiotic algae (zooxanthellae) which are believed to be part of the feeding and life maintaining requirements of them. They need to have high intensity lighting (often provided by halide lamps) to simulate sunlight with the required spectrum. If the lighting is off for a few hours, it is not a problem, but longer periods can be an issue. In that case one is looking at more than a few tens of watts.
.andy
To email, substitute .nospam with .gl
Keep going! Accumulator capacities are traditionally given at the
10-hour rate - so 40 Ah means you'll get 4 amps for 10 hours. At 20 A the capacity will be seriously less, although I won't try to put a figure on it.Also the discharge end-point is normally taken to be 1.8 V per cell - i.e. 10.8 V for a 12V battery. Make a habit of discharging a car battery that deeply and you'll seriously shorten its life - this is where the deep-discharge type of battery is needed.
Or use a dry pump, and do the rest with air pressure.
If I needed to worry about power dropouts long enough for lighting to be an issue, then I'd look at a generator.
What I intend to run in an emergency is 2 pumps ( a 45W + 110W ) + the controlling computer, which is a specialist aquarium controller < 100W and a small pump which is part of a organic waste extaction device=11W.
I think that UPS is the way to go, I need to research whats available on Ebay. I did come across a compaq 3000Va model fairly cheap. The problem with the UPS is the size and weight, does it have to be close to the tank, ideally I would put it in the loft ..( 2 floors up ).. Also is it possible to add additional external batteries to all UPS's. I'm thinking what about buying a smaller ~1000Va UPS and adding a 100AH leisure battery to increase the duration..
I would latter buy a small genny which I could use if the outage was over a few hours.
Thanks for all the input
..Tony
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