Vinegar is weak so takes some time to work. Citric acid is cheap and comes as a powder so you can mix it up much stronger; With electrolysis I found the red rust converts to a much softer black version. These black residues are easily dissolved off with citric acid. But remember acids will slowly attack steel so I would not leave a strong solution of citric acid (any strong acid solution) in a tank for more than an hour or two.
I saw molasses mentioned on YouTube but do not know how good it is. Maybe someone on a farm with horses may have tried it??
I saw molasses mentioned on YouTube but do not know how good it is. Maybe someone on a farm with horses may have tried it??