Sodium Thiosulfate

Does anyone know what, on average, is the length of time it will remain
active and at what concentrations does it become toxic to fish. In both
short immersion exposure and over long term immersion exposure. As well as
what (if any) are the tell tale signs of thiosulfate toxicity.

In a reef, you are shooting for high redox, not low. Use
only what you need to disable tap water Chlorine.

Matt Awbrey wrote:
Does anyone know what, on average, is the length of time it will remain
active

Thiosulfate is unstable in solution. Solutions of
thiosulfate break down into sulfur, sulfites, and sulfates
when exposed to acids, light (think reef), metal ions (reef
again), bacteria (yea, reef), and various oxidizing agents
(also reef).

Time in solution depends on how many destructive agents you
bring to bear on it.

and at what concentrations does it become toxic to fish.

Thiosulfate is a strong reducing agent, it will consume
dissolved oxygen. This fact will likely kill the fish
before any concentration of thiosulfate becomes toxic.

In both
short immersion exposure

Why would one ever want to do this? Anyway, O2 starvation
won't take long.

and over long term immersion exposure.

There won't be any such thing. Either the ion will degrade,
or the O2 will be set to 0 for a time and the fish will die.

As well as
what (if any) are the tell tale signs of thiosulfate toxicity.

Dead lifeforms.