Storing hydro nutrients in stainless steel 304 beer keg

Any thoughts on the topic? I have a beer keg around and was wondering if its safe to use for storing hydro nutrients?
I did some digging and there is controversial info out there.

I cant find reliable info if the keg’s going to rust nor if its safe enough for the plants and human consumption of the fruits that they produce.

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304 is one of the most common (if not the most) grades of stainless. Something like 10% nickel & 20% chromium IIRC.
I can’t see that being a problem.


Like mixed nutrients or concentrated liquid?

SS is called stainless for a reason, you’ll need something more corrosive than hydro nutes to cause any problems, I’d imagine.

Its a common misconception that SS does not rust. There are different types of SS with different corrosion resistant levels. Even the most higher resistant once corrode under specific conditions and exposure to certain chemicals like Hydrochloric and Sulphuric acids.
For example SS 303 is one of the worst SS in terms of corrosion resistance. 304 is good to great, 316/316L are excellent.

The main cause of corrosion is the Chloride ions commonly found in salts, which we have in the nutrients. That is the reason why you cant use 303/304 in marine applications as it will rust super fast.
316/316L contains 2% to 3% of molybdenum, a hard, silver white metallic element used to toughen steels and increase corrosion-resistance in nickel alloys.

I’m planning to use a mixed diluted nutrients solution (not a concentrated one) in AAA system. So it will not be as concentrated as a normal hydroponic solution, but may be 1/3 to 1/2 of a normal concentration that one would tipically use.

Found this: - could be very useful for anyone that wants to compare the elements in the hydro solution against the corrosion chart.


Informative, sure, but hydro nutrients have much less chloride than seawater, which is mostly chloride ions, and much lower TDS in general. Aeroponic solution, fraction of that.

We ain’t storing concentrated mineral acids in it either. I use about 2.5mL of phosphoric acid to adjust pH down per 5 gallons, and my water is very hard. Think you’ll be fine.

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