Phosphoric Acid and Hoppers

[Harry]

What's the consensus here on using phosphoric acid in water hoppers to control rust?

I have a galvanized water tank with mild surface rust inside. Will the acid harm the zinc? Or, will it neutralize the rust and add life to the container?

Same question applies to cast iron hoppers.

Don't put phosphoric acid in a galvanized water container! You won't have the galvanize very long.

Phosphoric acid may remove rust, but it attacks the base metal, too. Leave it on too long and you'll find out.

Generally speaking, metal is protected from corrosion with an alkaline pH. If you want to protect your metal from corrosion, throw in a teaspoon full of TSP, tri-sodium phosphate.

Phosphoric acid + Galvanized = exothermic reaction as the zink is disolved into the acid. Only a certain amount of the zink can be disolved, but I wouldn't do it. Instead, I'd throw about 12 tea bags into the hopper full of water, and let it set for a while. The tannic acid in the tea will accomplish about the same rust conversion, it's just a different process. Stirr occasionally, do not add sugar, and serve to people you don't really like.