By Donna M. Recktenwalt
Cleanliness in our aquaria – the homes for the fish we keep – is an important aspect of fishkeeping.
We all know that.
Normal cleanliness, of course, varies from fishroom to fishroom and tank to tank, but usually involves such regular maintenance as wiping down the glass and lids, changing or rinsing out filter media, and doing regular partial water changes. All of these procedures are designed to keep our finned charges healthy and relatively happy.
Cleanliness varies, too, depending on the intended use of particular aquaria. Cleanliness in an established community tank, for example, may not be adequate for a breeding tank, or one used for rearing fry.
But what cleaning agents can you use to really clean and disinfect a tankafter disease has gained a hold, for instance, or when first setting up equipment long unused, or from another source?
Several effective cleaning/disinfecting agents suitable for aquatic use are available in many homes, including salt, household bleach, hydrogen peroxide, and clear ammonia. Other, less common but equally effective cleaning agents are ethyl alcohol and potassium permanganate. Each has its own set of advantages and disadvantages.
Whatever cleaning agent you use, be sure to wash down everything that is used in and around the tank. Not only the tank itself, to and including the rim, the sides and the cover, but also the filter and filter box and all intake and outflow tubing, both air and water. At the same time it’s a good idea to clean nets, temporary containers for fish or food, algae scrapers, and anything else that is used in and around your tanks on which pathogens could hitch a ride from diseased to healthy fish or tanks. This list can alsoinclude the plants, the gravel, and other fish.
Herewith, a brief overview of several cleaning agents.
Salt is perhaps the most commonly used cleaning agent for aquaria and related items. Incoming plants can be soaked in a salt solution to effectively kill or weaken a major proportion of unwanted “visitors” that sometimes sneak in among the leaves or roots. Poured on a damp rag, salt will scour and polish tank glass. Salt rinses away cleanly, although minor residual amounts will benefit most killifish.
Common household bleach (5% sodium hypochloriteClorox or its generic equivalent) does a fine job of disinfecting aquaria and related equipment. For most uses a mixture of 1 cup bleach per gallon of water (1:16) will work well. Some prefer a stronger mix, with 1 part bleach to 9 parts water. Either works effectively as a rinse, a net soak, and a general disinfectant. For most purposes, a brief soaking or rinse with the mixture is sufficient. For more worrisome pathogens, or to thoroughly sterilize equipment, let soak in the bleach solution for 24 hours.
Removing residual bleach may be difficult, although usually a thorough clear water rinse followed by air drying will suffice. However, plastics may actually absorb some of the hypochlorite. For plastics, an “airing out” period is essential. An alternate method is to give the cleaned items a thorough secondary wash with diluted acid or plain (white) vinegar, which is roughly 7.5% acetic acid. Dilute the vinegar 1:20 with water for a reagent that will destroy any bleach residue. A clear water rinse will then remove the acid. Do not add vinegar directly to the bleach solutionthe result will be toxic chlorine gas!
Hydrogen peroxide is used both as a bleach and as a disinfectant, and is commonly found in the medicine chest. Hydrogen peroxide kills bugs on contact. Most hydrogen peroxide comes in a 35% solution; a 5% solution is recommended for aquatic use. The solution decomposes rather quickly, leaving no residue, and it is easier on the hands than is bleach. Be sure to store any unused 5% solution in the refrigerator. Peroxide concentrate can become explosive if it gets too warmkeep it at 80F or less.
Clear ammonia. Most households have a container of clear (not sudsy) ammonia on hand. A 1:4 mix with water will sterilize almost anything and leave no residue behind. Ammonia may be rough on your nose, but it rinses away cleanly with several hot water washes. Any remaining traces will be broken down by the microbes in the filter bed, which handle this type of ammonia just as they do naturally produced ammonia in the tank.
Ethanol (ethyl alcohol). Although bacteria can live quite well in pure alcohol (190 proof), a 75% solution (150 proof) will work quite well to kill the majority of them. The solution destroys the cell walls of the bacteria, making it an effective disinfecting agent. Alcohol evaporates quickly, leaving no residue.
Potassium permanganate. If you enjoy working with what looks like dilute grape juice, try a 1% solution of potassium permanganate. Initially it will stain, but as it oxidizes organic material it produces manganese dioxide, a brown sludge. The cleanser is good for glass and plastics, but it isn’t recommended for such items as nets, breeding mops, or clothing. If you do get a stain where you don’t want it (on your clothes, for example), you can dissolve the stain by using hydrogen peroxide. — G.C.K.A. Newsletter, May 1997