Muriatic acid is a hydrochloric-based acid that causes damage to skin and eyes when exposed. The harsh acid also damages a variety of other materials and should only be used with extreme caution. Despite the potentially harmful side effects, muriatic acid is an effective descaler. Muriatic acid removes severe lime and calcium deposits found in areas where standing water is present such as pools and toilet bowls.
Descaling Toilet Bowls
Dilute the acid properly. Put on safety glasses to protect your eyes and rubber gloves to protect your skin. Fill a plastic bucket with four parts water to one part muriatic acid, diluting the acid to a 25 percent mixture. For example, use four equal cups of water to 1 cup of muriatic acid. Always add the acid to the water, never add water to the acid.
Pour the mixture into toilet bowl. Allow to sit for one hour to dissolve calcium and lime deposits. Once complete, remove all traces of the acid, especially if there is potential for the acid to splash up on skin. Flush the bowl several times before proceeding.
Use a stiff-bristled brush and gentle all-purpose bathroom cleaning detergent to scrub the toilet bowl, and flush again. Wipe away all residue with a dry cloth. Immediately dispose of or wash the cloth.
Descaling a Swimming Pool
Test for calcium deposits. Put on safety goggles and rubber gloves to avoid direct contact with the acid. Using a glass eye dropper, suction some muriatic acid directly into the dropper and apply several drops directly into a filled pool. If the water bubbles or foams, the pool needs descaling.
Use a descaling agent like Scaletee Plus. Apply 3 to 6 fluid oz. of the solution for every 1,000 gallons of pool water. This solution has muratic acid pre-mixed, acting as a long-term descaler and does not require you to manually dilute it. Allow the cleaning agent to circulate in the pool.
Add water to the pool until it is 1 to 2 inches above the scale line. Keep the pool pump on for 8 to 12 hours per day during the cleaning period. It can take 3 to 6 months to effectively descale a pool. The pump helps increase the circulation of the solution and descales the pool naturally without requiring laborious efforts in scrubbing and washing. After 4 weeks, lower the water level in the pool to normal levels.