Fallout wrote:

Hi

I have been trying to source a supply of dechlorinator that does nothing but
dechlorinate. According to my LFS the Tetra product only contains Sodium
thiosulphate, but the label says that it will also remove heavy metals.

I am not sure how soluble iron thiosulphate is, but thiosulphate is used
only in tiny amounts (it catalyses the chemical conversion of
hypochloric acid) and is rather unstable, so it won't last long in a
tank. For both reasons I would not expect it to have a major effect on
iron concentration.