By Donna M. Recktenwalt
Killikeepers know that many killies, particularly the Aphyosemion species, prefer softer, more acidic water. Many killikeepers collect rainwater; some have invested in Reverse Osmosis units to assure a continuing supply of suitable water for their fish. But might there be another answer?
The question of using water from dehumidifiers has been addressed a number of times, both in the printed media and on the various killifish e-mail lists. At best, the answers are mixed.
“I currently use a dehumidifier in my basement… In theory this water is as good or better than the RO water from my reverse osmosis system. Does anyone have actual experience using dehumidified water in their fish tanks?” asked Jim Langam in a recent e-mail query.
“We have successfully raised Rivulus xiphidius for two years,” say Norm and Susan Stacey, “in 6 parts dehumidifier water to 1 part tap water. We fill a funnel with charcoal and pour the dehumidifier water through the charcoal and into a plastic container before it’s used. We also add oak leaves to the bottom of the breeding tank. The fish seem to be happy, and we’ve never had a problem. Note that the humidifier is fairly new and we have only tried using its water with R. xiphidius, since they like soft, acidy water.”
In the opinion of Julian Sprung, who writes the “Reef Notes” column for Fish and Marine Aquarium, dehumifier water is unsuitable for aquarium use because it has been condensed on an aluminum coil.
From Aquarium Fish Magazine, September 1998, comes the following: “It might be possible that water forming on the coils could pick up trace amounts of aluminum, zinc, or copper. And, as the water condenses, it could absorb compounds from the surrounding air, such as nicotine from cigarette smoke, compounds from household cleaning products, and so on.”
Of course, the “topoff” water requirements of a reef tank do not pose the same requirements as water used for water changes in a freshwater, often slightly acid tank.
If you have a dehumidifier, it might be a safe and easy alternate water source for your killi tanks. But do some careful testing and experimentation first. If the results look good, try some of that dehumidifer water in a tank or two. Use care, take careful notes, and let us know how dehumidifier water works for you.
— G.C.K.A. Newsletter, September 1999