In a fish pond, the pump plays a vital role -- literally. Without a pump, water carrying oxygen will stay near the surface or near the aerator where it was introduced. This is when you’ll see your fish hovering at the surface, gulping for air. Imagine yourself in an aircraft at 35,000 feet when the cabin pressurization fails. Without those attractive yellow masks, there’s just not enough oxygen up there to survive. It doesn’t sound like a pretty way to die. Aside from suffocation, there are other grave consequences for your pond’s ecosystem from removing or turning off a pump. Without oxygen, for example, beneficial microbes will soon die and release toxins into your water, raising ammonia levels. Nitrate levels will also rise, encouraging algae blooms. All of these pose serious dangers to your fish, even after a pump has been turned back on. It’s an emergency situation and it could take days of frequent testing and careful rebalancing of your water’s chemistry before you reach equilibrium again. In other words, pumps need to operate 24 hours per day, 365 days per year.
In an emergency, the exact amount of time your fish can manage without a pump depends, of course, on a variety of factors. A few seconds will probably be ok. A few minutes could be bad if you have a very high fish load or your oxygen levels are on the low side. An hour could be catastrophic or may just leave your koi gasping for air. It’s not something we’d recommend testing out. One solution could be to make sure you consistently maintain a high level of oxygenation so there’s some wiggle room in case of an emergency. If you’re concerned about an electric outage, a catastrophic pump failure, or even maintaining or upgrading your current pump, you’ll want to be prepared in advance so that your fish don’t get severely stressed, injured, or even die. A backup pump at the ready with a UPS (battery) device can keep your pump going for an hour or so, depending on the size of UPS and the wattage of your pump. If your power outages are frequent and extended, a generator may be in order.
