MAP acceptable as nutrient?

[dragon613]

Is MAP (mono ammonium phosphate) an acceptable substitute for DAP yeast nutrient?

If so then I have hundreds of pounds of yeast nutrient for free I didn't know about. (Buckets of MAP emptied out of scrap fire extinguishers) and I can stop paying $6 a pound at the brewshop

Someone asked on stackexchange and everyone said it "should" be fine but nobody who had actually tried

[Expat]

So with some quick research, MAP is water soluble and used as a fertilizer so in that sense I suspect it would work.

Where I would have serious reservations is the OTHER stuff which might be included in fire extinguishers; for example ABCs typically include ammonium sulfate, which is also a fertilizer but... what else might there be?

[dragon613]

That's a good question, I'll ask my buddy at the fire suppression company if he's got an MSDS for the fill

Edit: after going through half a dozen MSDS the non MAP components are( is descending order of frequency)

Ammonium sulphate (listed as a "yeast food" by my states anti distilling laws)
Calcium carbonate <2.5% (sold by my brewshop as pH buffer)

These are in pretty much every abc mix, the following are only In certain mixes (when emptying extinguishers some are filled with white powder, some are filled with yellow)

Mica
Kaolin clay
Amorphous silica
Silicone oil
Yellow coloring

[zapata]

I'd be mildly concerned about the purity of those ingredients though. Clay and mica for example can have heavy metals. Not to mention even the main ingredients are bound to be rough technical grades, with very little concern for what impurities they have. Sure, the amounts are bound to be small, the dosage rate is small, but, who knows?

Personally, well, I used to make wash from miracle grow and other fertilizers, so I'm flexible. But I do admit it bothered me a bit, and now I pretty much only use food grade anything to feed my yeasts.

[Chucker]

Bear in mind that the MSDS is not a recipe sheet nor should it be considered as a comprehensive listing of everything in there. They only have to list those substances considered as hazardous. Free stuff is always good but sometimes it’s still not worth the price.