If there is standing water in the toilet or tub, bail it out with a bucket. Chemicals are heavier than water, but if the water is deep, the chemical will dilute before it reaches the clog, rendering it useless and leaving you with a tub full of toxic waste.
Pour hot water down the drain to flush the chemical and the dissolved clog into the main sewer line. how to unclog a sewer line with chemicals
The clog is likely solid (tree roots, a broken pipe, hardened grease, or a non-organic object). Repeated chemical use will not work and will only damage your pipes. If there is standing water in the toilet
Common in kitchen lines, these substances solidify and trap other debris. The clog is likely solid (tree roots, a
Open windows. Turn on bathroom fans. Chemical fumes are lighter than air and will rise; you do not want to be huffing lye or sulfuric acid vapors. Wear rubber gloves and safety glasses. If you have a respirator mask, wear it.