Quiz: How to keep a reef tank alive with a battery?

taricha

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Here's the (hypothetical) situation:
You have a medium sized reef tank (50-100 gal). There's a power outage and you have a small appliance battery and an AC converter. What do you run on the battery power to keep the system alive with as little disruption as possible - little to no loss of fish and coral?
To be specific, the power outage will last 3 days (72hr) . Your battery is a 12V, 100 Amp-hour model like this. You have an AC converter so you could run any of your plug-in equipment. The tank is in a location where the temp will be stable enough to not be a big issue.

Would you run airstones for O2/gas exchange with the idea that it'll also provide enough flow?

Would you run a powerhead for flow with the idea that flow across the surface gives enough gas exchange?

Would you run LED lights near-continuously for 72hr to produce O2 by photosynthesis?

Would you do some combination? Do something else entirely? Do you think it's impossible?

The most helpful responses would be specific, with approximate wattage of equipment since you have to make it 72 hours on 12V, 100 Amp-hours battery.
 
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taricha

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P.S. I failed this quiz a like 10 years ago when it came up (ran too much, assumed power would be on by the next day - lost a bunch of stuff). I think I know what I'd do now, but curious to hear others' ideas.
 

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Maths and equations are not my best abilities, if in worst case scenario could you not use your car battery for a period of 4 hrs ? Start up car again to recharge battery by (starter motor) correct me if I'm wrong , for 1 HR then car battery will provide another 4 HR hrs of power?
 
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TheBear78

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Anything that you can cycle on and off immediately uses 50% less power (assuming equal on/off periods).
If it was me and I was lucky enough not to need heaters I would run the return pump in something like a 15 minute on 15 minute off cycle and run the lights at a lower intensity for a shorter time. I don't think that having the lights cycle on and off would be very good for the fish.
I would worry about additional circulation unless I had an abundance of power.

I couldn't open the link but most (non Lithium) 100AH batteries are only good for 50 - 80 AH before they're ruined.
 
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Not sure what the best answer is but, if it were me, I think I'd:
- avoid the AC inverter if possible, too inefficient
- battery powered air pumps with air stones
- DC power head for flow if you have one you can rig up

*are you home during this time or away?
*summer heat would be my other concern
 
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taricha

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*are you home during this time or away?
Let's say you are mostly home before and after work (normal schedule) and can adjust things to give you the best chance of success.

I would not use the adapter; too much power loss.
aha. I neglected the inverter loss. Quick look around suggests they are 10-30% inefficient?
Not sure what the best answer is but, if it were me, I think I'd:
- avoid the AC inverter if possible, too inefficient
- battery powered air pumps with air stones
- DC power head for flow if you have one you can rig up

so let's take as given that if you have a DC airstone or pump you should use those over anything you needed to run off the AC inverter, and it would improve outcomes in terms of 10-30% more juice.

For those wondering....
Theoretically, I think 12V 100Amp-hours calculates to 16.7 watts for 72 hours.

So how would you use 16.7 watts to keep a reef tank alive for 72 hours? (If you have to use an AC inverter which may be 30% inefficient, you may only have ~11.5 watts.)
 

vlangel

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I actually had a situation similar to this happen to me. I have a 56g column display tank (with over 10 fish) that drains into a 30g fuge/sump.(that has 2 fish). I have Penn Plax battery back up on both tanks for automatic aeration if the electricity goes off. I also have a 1000 watt power inverter in case of a longer power outage which for 30 years had never happened at our house. Unfortunately (a few years ago) a tree fell during a storm a few doors down taking out a natural gas line so the power company had to wait on the gas company before restoring electricity to our street. Anyway, it was winter, so we were without heat and electricity for about 4 days. Fortunately, we have a fireplace about 10ft from the display tank, so temperature was not much of an issue. We hooked the inverter up to our car and let the car idle. I chose to run an extension cord to the return pump and lights alternatively. We even charged our laptop and had the fridge on the extension part of the time. The aquarium system had absolutely no negative effect from the power outage whatsoever. For me a power inverter is the way to go. That way there is no fussing with a generator to make sure that it will start when it's needed, and no storing a big generator in the garage (I keep the inverter behind the sofa next to the aquarium). I could have kept my aquarium going indefinitely with that.
 

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What about them jar things that produce oxygen and a battery air stone ?

Sochting oxydator they called ( just googled it ha ha )
This would require least amount off power I would off thought.
Never used one and not sure if would work but as reading threads on them over the years,that was idea I thought could be used for in power outage,if already have running in tank and power outage happens then you already set up for it.
Just an idea
 
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Oregon Grown Reef

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I weathered a nasty ice storm a couple of years ago with this exact power setup. Since it was freezing, I did have to worry about the heat. I swapped out both of my car batteries and use an inverter to power my return pumps/powerheads. After the temp dipped below 70 degrees, I then plugged in the heater and swapped out the batteries sooner. I did not need to provide them with light. My thinking was they often go through dark periods during storms in their natural environment, so I wasn't too worried. I lost nothing during that time.
 

Erin1971Texas

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Not sure what the best answer is but, if it were me, I think I'd:
- avoid the AC inverter if possible, too inefficient
- battery powered air pumps with air stones
- DC power head for flow if you have one you can rig up

*are you home during this time or away?
*summer heat would be my other concern
This is my answer too.
Battery air pump and DC wavemaker.
 

Dan_P

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Here's the (hypothetical) situation:
You have a medium sized reef tank (50-100 gal). There's a power outage and you have a small appliance battery and an AC converter. What do you run on the battery power to keep the system alive with as little disruption as possible - little to no loss of fish and coral?
To be specific, the power outage will last 3 days (72hr) . Your battery is a 12V, 100 Amp-hour model like this. You have an AC converter so you could run any of your plug-in equipment. The tank is in a location where the temp will be stable enough to not be a big issue.

Would you run airstones for O2/gas exchange with the idea that it'll also provide enough flow?

Would you run a powerhead for flow with the idea that flow across the surface gives enough gas exchange?

Would you run LED lights near-continuously for 72hr to produce O2 by photosynthesis?

Would you do some combination? Do something else entirely? Do you think it's impossible?

The most helpful responses would be specific, with approximate wattage of equipment since you have to make it 72 hours on 12V, 100 Amp-hours battery.
12 V 100 ampere hour is the same as 120 V 10 ampere hour but I need almost 100 hours of power, so, I better only use about 1 ampere per hour

My goal would be to minimize anoxia.

O2 in /CO2 out most critical to maintain. Not sure whether power head circulation or bubbling air is better. I would make the selection based on the lower energy user. If after looking at power usage I could run a small powerhead and a bubbler, I would do both.

The lighting is interesting consideration. I might think about 6300 K LED spotlights (how many depends on wattage) that I would mount at or under the water surface for maximum brightness. I would run them six hours and overlap the current light cycle, shortening your current light cycle appropriately at both ends.

With an approximate 120 watt budget, I might spend 60-80 watts on air exchange and 20-40 watts on lighting not so much for O2 production but for my coral and algae. The 20-40 watts is not much like output so maybe I would consider buying some mirrors and get daylight on my tank.
 

flashsmith

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I just had to run my tanks for 2.5 days without electricity. I ran my return pumps at about 25-30% using an inverter and 2 deep cycle marine batteries. One tank a reefer 625 and an IM SR80. Everything survived with no issues. Both tanks are heavily stocked with fish and corals. The decision to go with controllable DC pumps proved to be a good one for me.
 
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Bubble aeration always beats surface aeration.

aeration 11.png
 

Randy Holmes-Farley

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I’d opt for a powerhead over an air stone, watt for watt, but I expect it depends very much on the placement of both devices.
 

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