I have one fermentor that is crudded up with beer stone. The first thing I did was quit using it (because sanitation issues), but for the last week I have been exploring ways to remove the stuff.
Beer stone is said to be calcium oxalate in an organic matrix. In my case it's a hard, chalky, white deposit that ranges from the fill line to about 5 inches below it. Thus far I have attacked it with:
1. A concentrated (37.5%) HCl rinse: No effect.
2. 6 molar tri-sodium phosphate: No effect.
3. 85% phosphoric acid rinse: No effect.
4. EZ-Off oven cleaner (contains NaOH) which was mentioned in a web article on beer stone: Minimal effect after three 24 hr applications.
One article mentioned that HCl was effective in removing beer stone. My earlier negative results may have been due to limited contact time, so this evening I prepared 5 gallons of 7.5% HCl (equals 2.42 M) by diluting one gallon of 37.2% (12.1 molar) swimming pool grade HCl to 5 gallons with tap water in the offending fermentor. I'm going to let it soak overnight and see what happens.
Have any of you found any quick easy way to remove beer stone?
NOTE: This fermentor is a 7.5 gallon HDPE plastic bucket. I would never use HCL in a stainless vessel!
Charlie