Quote Originally Posted by badflash
I have now found why phosphoric acid and not other acids are used to make this stuff. If you use other acids and then neutralize them, you end up with salts that are no good for plants. Muriatic acid gives you regular salt, sulphuric acid give you sulphates. Phosphoric acid gives you phosphate that plants like.

Be sure your container is closed tightly or you get unwanted guests. ewww!
I was just about to suggest sulfuric or hydrochloric acid (muriatic acid). The HCl would release the chlorine and that would volatilize into the atmosphere. If you have any doubt, you can always boil the mixture before adding your other compounds that would create salts. When you boil water, the chlorine cannot stay soluble and will undoubtedly volatilize into the atmosphere.

As far s the sulfuric acid forming sulfates, the sulfates should serve as fertilizer just like the phosphates.

Sulfuric acid, battery acid, is very cheap. And as you know, muriatic acid, hydrochloric acid, is also very cheap.

Food grade should really not be an issue for these kinds of chemicals because their so reactive they simply can't be mixed with many substances.

Home Depot $27
Miracle Sealants 128 oz. Fast-Acting Phosphoric Acid Cleaner

Try the pool or hardware stores. They should have it for cheaper than online. You should always check the MSDS, and I can help you look if you want, but again I doubt it will be mixed with anything at higher concentrations because it's so reactive.

EDIT: Found this too: http://compare.ebay.com/like/1703784165 ... r&_lwgsi=y (it's weaker at 52%, but it's $27.88 free shipping, if this was 85% you would pay $38.84 so it is CHEAPER than the one you mentioned above)

This is 2 gallons of the above with some more savings: http://cgi.ebay.com/Phosphoric-Acid-52- ... %26ps%3D54

Local will always be cheaper due to shipping.