Do you have Heinz cleaning vinegar (20% acetic acid) that’s sold the gallon?

Believe so

Yes

I purchased the 6 % solution. Stronger concentrations may be available elsewhere.

Aisle A8 Heinz cleaning vinegar 6% Acidity. From what i can see on their website for Kenai store. It doesn't carry anything higher Heinz wise. You may have to special purchase through their website, Amazon or choice internet store.