There are certain functions in a saltwater aquarium which are essential for its survival: gas exchange and water movement. Even the most sensitive corals in a reef tank can survive for days without intense light, but the viability of fish, invertebrates, corals and beneficial bacteria deteriorates rapidly without a reasonable supply of oxygen. This being the case, in the event of a power failure, the primary objective (both short and long term) for the aquarist is to supply oxygen to the tank and move water (even periodically) about in the tank. This is bare bones survival and some of your tank's filtration systems (wet/dry trickle, canister filter) will not be functioning. The nitrifying bacteria which resides in the tank (on the live rock, tanks walls, etc.) will live and continue to process ammonia, nitrites and nitrates if O2 is supplied at least periodically.
For most tanks, when operating properly, a vast majority of gas exchange (CO2 out and O2 in) takes place at the water surface of the tank. Protein skimmers and wet/dry tickle filters also contribute to gas exchange during normal operation, but will not be functioning during a power loss. You can supply O2 to the tank and provide some water circulation manually. Here is one method which is easy to do and actually works:
- Take any type of clean cup, pitcher or other container, scoop out and fill it with aquarium water.
- Hold the filled container some distance above the aquarium, and pour the water back into the tank. Repeat this process numerous times.
Tip: A larger volume of oxygen is generated the higher the water is dispensed from above the aquarium, and the number of repeated times this is done.
More Oxygenation Tips
- There is no set rule on how often this should be done, because every aquarium is different. You'll need to judge for yourself at what intervals each hour is going to be best for your system. When in doubt, go ahead, and if the fish start coming to the surface gasping for air, it's definitely time to aerate some more.
- To avoid messing up the substrate and stirring up a bunch of crud, particularly if you have a small or shallow aquarium, place a small plate or bowl in the tank and pour the water onto this area. Ceramic or glass items work well for this, because the item has to be heavy enough to stay submerged and in place.
We recently had our own power outage experience, which taught us a lot about aquarium survival without electricity.
With Hurricane Irene approaching, the lights started flickering Friday evening. We shut down the computers, lit the candles and placed flashlights in convenient places in the house. We unhooked the UPS from the computers and placed it next to our 92g saltwater aquarium. The lights finally died for good at about 9:00 PM. We plugged the aquarium sump return pump into the UPS and started running it for a few minutes every half hour or so. This worked for a few hours, but the UPS finally gave out (the pump drew too much power).
Deb started aerating the tank with a 2 quart pitcher, dipping water out of the tank and poring it back in from a couple of feet above the surface. We also plugged in a small battery powered air pump and dropped an air stone into the tank. The battery powered air pump only produced bubbles to about 16" of depth.
On the third day, we lost the large Naso Tang, Pacific Cleaner Shrimp, Japanese Swallowtail Angelfish, Yellow Tang and Firefish Goby. The surviving fish (Hippo Tang, Fire Clownfish) were transferred to our 12g tall Seahorse tank, along with the battery powered air pump and air stone. They did extremely well through the power outage and were returned to the 92g once the power came back on and a major water change was performed.
Ironically, all of our corals which were left in the 92g did extremely well. Most of them lost their colors, but their resident zooxanthellae algae recovered after a couple of weeks and the corals' color was back to normal.