Please choose the correct ending to complete the given sentence: Home and Garden: [header] How to use a chemical drain cleaner [title] Understand what drain cleaners do. [step] Chemical drain cleaners or openers usually rely on a strong acid or alkali to do the job. These substances both break down and dissolve the clog, and react with the water to form heat.

Ending1: [substeps] Drain cleaners work best on slow moving drains. They are less effective in clogs with standing water. Ending2: The acid reaction heats up the drain created by the acid or change the water as a result. When wax or other wet surface has dissolved into the water, the plug changes in the water and any moisture drains out. Ending3: Draining, then remove, siphon off the resulting air and the bottled water and discard. The simplest additive for a cheaper drain cleaner is acetone. Ending4: [substeps] Drain cleaners aren't necessary for treating plumbing leaks in apartments or buildings. They're not recommended for residential systems where overheating is a major hazard.

Answer format: ending1/ending2/ending3/ending4