Managing Power Outages

There are a few moments in the journey through being an aquarist that you'd rather not be a part of, but sooner or later everyone hears the hum of the filter cut out as the light goes dark, and the home gets quiet in a way that you haven't heard in a long time, and DEFINITELY feels wrong. Maybe a storm rolls through, perhaps a transformer blows a few blocks over, or someone decides to run three hairdryers at the same time in the same outlet and a breaker trips. Suddenly the microcosm of an ecosystem we've spent months or years building and tuning is just surviving on nothing but the water already in the tank. PANIC!!! Wait, no. It isn't a reason to panic, it's a reason to have a plan, because a freshwater aquarium doesn't fail the instant the power does, it fails on a timeline, and a timeline is something we can work with.

The first thing worth understanding is that three systems are quietly unraveling at once the plug goes dead: temperature, water quality, and oxygen / carbon dioxide. They don't collapse at the same rate, and they don't threaten the same fish in the same way, so it helps to think about them separately even though, as we'll get to, the fix for all three often comes down to the same simple action.

In the first stretch of an outage, most established tanks are coasting on stored heat and stored oxygen. Water has some thermal mass, and usually isn't too far off your ambient room temp. A heated tank in a room at normal indoor temperature will drift down gradually rather than crash when the juice gets cut. A well-stocked, moderately sized tank can often go an hour or more with barely a detectable shift, and if you have a room that is the same temperature as the aquarium, you honestly didn't need a heater to start with, it will stay the same as the ambient temp. This is the best-case scenario, because at least temperature isn't something you're going to have to worry about.

This is the window to simply note when the power went out, check the thermometer if you have one, and resist the urge to do anything drastic. Leave the top on, and don't panic. Overreacting in the first hour dumping in warm or cool water, cracking the tank open and stirring things up — usually causes more stress than the outage itself has caused so far.

Once we're a few hours in, the calculus starts to shift (dang, how long is this storm going to last anyway?!?) Temperature loss is still usually gradual and forgiving for most community fish, but oxygen can be different story. Without a filter or air stone agitating the surface, gas exchange slows to a crawl, and a heavily stocked or heavily planted tank (remember, plants consume oxygen at night) can start running an oxygen deficit well before the water feels noticeably cooler. The best move here is preparation: locate the battery-powered air pump you have for just this occasion. If you don't own one yet, go buy one now, before you need it, they can be inexpensively sourced from your LFS or even a bait shop. A battery bubbler is inexpensive insurance and the single best piece of gear for exactly this scenario. If you're reading this during the power outage and no one has given you this advice before, we're sorry. That said, all is not lost; you can agitate the water's surface manually. Remove some water and pour it back into the tank (like with a large glass or pitcher), even swirling the aquarium water around with a net will help get some oxygen back into the tank. We'd also start thinking about a partial water change with dechlorinated water that's close to the tank's current temperature, not because water quality has degraded much yet, but because a modest exchange reintroduces oxygenated water and helps buy time on two fronts at once. Fresh water pulled from a tap (if your water source doesn't contain chlorine or chloramines) or a stored reserve (preferred) is typically closer to room-oxygen saturation than the increasingly stagnant water sitting in the tank, and if it's held at a reasonable ambient temperature, it can also nudge the tank's temperature back toward stable rather than letting it keep sliding.

Past the half-day mark, nitrogenous pollutants and waste buildup can start becoming a factor alongside oxygen and temperature, especially if your display is heavily stocked. (Wow, what is going on with your power grid?) Without biological, physical or chemical filtration, waste isn't being processed. This is where we are advocates for small but frequent water changes rather than one large exchange, which can shock fish that are already under stress. A 10 to 15 percent change every couple of hours, using water matched as closely as possible to the tank's current temperature does triple duty: it removes / dilutes accumulating waste, it reintroduces oxygen, and it slows the temperature drift. If the outage is happening somewhere cold, and the room your aquarium lives in is dramatically different temperature wise than the aquarium itself, wrapping the tank with towels or blankets (never anything that blocks manual access) can insulate it, slowing heat loss, which just might buy you some more time.

Beyond twelve hours: high concern, active intervention – dang, that's quite the outage!

If we're past the twelve-hour mark with no end in sight, it's time to treat this as an active emergency rather than a waiting game (this is quite the outage, that storm must've been crazy). The battery air pump you bought in hour one should obviously still be running. If the ambient room temperature has dropped significantly and the species in the tank are sensitive to cold (many tropical community fish begin showing stress when the temp gets into (and under) the low 70s. If possible, start to warm the water you're doing water changes with, if the gas is still on and you can run a range top, or perhaps you have a camp stove (or turkey fryer etc) outside, warm water changes can help hold the line. Just be careful not to overdo this. You're not going for full temperature recovery all at once, we don't want to shock our fishy friends. On the other end of this extreme is our friends in the southern US who often have large storms in the summer months, and temperature rise is a real possibility when the air conditioning is out. This is a much worse problem as low temperatures can be stressful, but high temperatures kill fish much faster. Luckily all the ice we know of in the United States that is sold in bags is safe to use in your aquarium. Adding a whack of ice to the water for your water change can help lower the temperature. Be very cautious adding it directly to the aquarium, but this can also be done.

The throughline across every stage is that water changes are doing more work than most hobbyists give them credit for during an outage. We tend to think of them purely as a nitrate and ammonia tool, but in a power-loss scenario they're also our best mechanism for oxygenation and our most controllable lever on temperature. Minimizing casualties is also heavily correlated to preparation. Keeping a jug / bucket / garbage can or two of dechlorinated, temperature-appropriate water on hand, alongside a battery air pump, and maybe even a back stock of ice can turn a stressful situation into a manageable one. Fish are often more resilient than we assume, (especially to slightly lower temperature). If you're the kind of hobbyist who has a fish room (instead of an aquarium or two) your preparation for this kind of event should probably include a portable generator and a few extension cords. An aquarium that's monitored and tended through the first twelve hours of an outage rather than left alone and hoped for, gives you and your fishy pals the best chance of making it through the dark times unscathed. If you haven't already, head to your LFS ASAP. Get a couple back up 5-gallon jugs of water (depending on your aquarium size) and a battery-operated air pump, air hose & stone right now. You'll never be sorry that you did. Tell them Aquatropic sent you.