Draft line cleaning uses two kinds of chemical. Caustic (alkaline) cleaner goes through every two weeks. Acid cleaner goes through every three months. They remove different kinds of buildup, so a system needs both.
Caustic Cleaner: Every Two Weeks
Caustic cleaner has a high pH. It breaks down organic buildup: beer protein, yeast, and the biofilm bacteria build on the tubing wall. It's the cleaner used at every routine visit.
The Brewers Association Draught Beer Quality Manual calls for:
- 2% caustic for routine cleaning, 3% for dirty or neglected lines
- Solution temperature of 80 to 110°F
- At least 15 minutes of recirculation with a pump
Too weak and it won't break up the biofilm. After the cleaning, the lines need a full water rinse. Leftover caustic will ruin the next keg and can burn someone. See biofilm in draft lines for more on what caustic is up against.
Acid Cleaner: Every Quarter
Acid cleaner has a low pH. It dissolves mineral buildup that caustic can't touch. The big one is beer stone, a crust of calcium oxalate that comes out of the beer itself. Acid also removes water scale.
The Brewers Association recommends an acid cleaning every three months. Line cleaning acids are usually phosphoric acid based. Learn more in what beer stone is.
Order Counts
On a quarterly visit, caustic goes first. It strips the organic layer off the top. Then the acid can reach the mineral underneath. Then everything gets rinsed with clean water before beer goes back in.
What About One-Step Cleaners?
Some products claim to handle both jobs in one pass. We stick with separate caustic and acid steps, which is how the Brewers Association lays out the process. If a cleaner uses a one-step product, ask how they handle beer stone.
What Happens If Acid Gets Skipped
You won't notice right away. Beer stone builds slowly. Over a year or two, lines get rough inside, hold on to bacteria, and pour more foam. Off-flavors come back sooner after each cleaning. See off-tastes in draft beer.
Handle Both With Care
Caustic and acid line cleaners both burn skin and eyes. Wear gloves and eye protection. Never mix them. Rinse the lines well after each one before beer goes back through.
If your lines haven't had an acid cleaning in the last three months, they're due. Call (267) 282-1002.