Can you overdose on chlorine remover? – Tip 8 in the Water Series

It is extremely difficult to overdose on chlorine remover. The active ingredient in most chlorine removers is sodium thiosulfate. It is a chemical that, when used sensibly, will not cause any harm to fish or other living organisms in the aquarium. This is especially true when using a commercial preparation to dechlorinate water before adding it to the tank. In cases like these, ten or even more times the dose will not cause any harm. Although sodium thiosulfate can be purchased in bulk, we don’t recommend trying to add the neat chemical to water. The dosage would be quite high in this concentrated form. But, even in circumstances like these, it’s rare to experience overdose problems when used to remove chlorine.

The use of this chlorine remover results in a chemical reaction, the chlorine is neutralized and a white precipitate is formed. In most cases, normal water maintenance with a gravel cleaner will remove this precipitate from the tank and there will be no chance of further reactions and prevent an overdose of chlorine remover from occurring. However, there is one case where the use of a chlorine remover has been seen to cause serious problems in the habitat. It is extremely rare; and requires very specific conditions. However, when they are met, the chemical reaction is reversed and the chlorine is released back into the aquarium, often killing the fish in the process.

The problem I am discussing requires an aquarium situated in a location where the water supply is treated with chloramine, not chlorine, as this requires at least a double dose of chlorine remover to break the original bond of chlorine and ammonia.

The second necessary condition for a reverse reaction is that the tank is poorly maintained, if at all. This is where partial water changes do not exist and water is replaced only when the evaporation level is too great.

The third condition is that the dechlorinator has a heavy overdose every time new water is added. The need to remove chloramine often results in severe overdosing of replacement water with chlorine remover. Over time, the precipitate will accumulate in the substrate, since regular cleaning of the gravel is not done to fix it.

After about a year or two of this neglect, and a heavy overdose of chlorine remover, the phenomenon where the chemical reaction is suddenly reversed can occur. Instead of neutralizing the chlorine by adding a water conditioner, chlorine is actually released. In this extraordinary case, the chlorine accumulates instead of dissipating and no amount of chlorine treatment will remove it.

At this point, it is often best to do some serious maintenance on the aquarium, before it returns to harboring life.

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