The 10 Best Acid Cleaners

Anyone who needs muriatic acid's strength for concrete, brick or a pool, without the choking cloud, should start with Certol Acid Magic. It's used full strength, and the maker says buffering keeps it from burning intact skin and cuts fumes by about 90 percent. It etches concrete before sealing, lifts mortar stains and lowers pool pH. It's still a corrosive acid that attacks metal and etches stone, so goggles, gloves and a thorough rinse are still part of the job.

For crusty faucets, foggy shower doors and rusty sink rings, CLR Calcium Lime & Rust is the gentle place to start. This trigger spray comes ready to use, so there's nothing to measure: spray, wait a minute or two, wipe and rinse with water. It carries the EPA's Safer Choice label and is safe for septic systems, with no ammonia or phosphates. Thick, years-old scale can take several rounds, and it isn't meant for marble or other natural stone.

Tile setters reach for sulfamic acid to clear the cloudy film grout leaves behind, and Custom Building Products TLSAC1 is a classic tub of it. The crystals dissolve in water, so there's little vapor, and the maker says the solution is safe on colored grout. It also removes dried mortar, the white powder that seeps out of brick and hard-water spots. It can etch some glazed tile and has to stay off marble and polished stone.

Rust rings and hard-water lines under the rim are what Zep Acidic Toilet Bowl Cleaner is made for. The thick gel holds about 10 percent acid, and the angled neck lets you squirt it under the rim, where it clings to the sides instead of sliding straight down. It's meant for toilets and urinals only, not tubs, counters or tile. Never use it with bleach or another bowl cleaner, since mixing them can release toxic gas.

Kettles, coffee makers and dishwashers get a gentler treatment from Milliard Citric Acid, the same food-grade powder people use for canning and candy. Dissolved in water and run through a cycle, it loosens the white crust inside appliances, and as a mild acid it's far less likely to harm metal parts and seals. The resealable bag holds enough for many rounds of descaling. It works slowly on heavy rust and thick, stony scale.

Miracle Sealants HDAC is a liquid concentrate for tile floors where grout haze, white mineral bloom or rust stains won't budge with soap. You thin it with water for routine cleaning or use it stronger for stubborn spots, and the label lists ceramic, porcelain, slate and unpolished stone. Try it on a hidden spot first. It's a strong acid, so it can dull marble, limestone or any polished stone it splashes onto.

On a tight budget, Zep ZUCAL32 packs concentrated acid into a cheap quart jug. It goes after crusty deposits on porcelain toilets and sinks, cement, stucco, glass and fiberglass. Zep's own warning list matters here: keep it off wood, fabric, natural stone, aluminum, brass, chrome and painted surfaces. That rules out most faucets and shiny trim, so it suits fixtures and masonry better than hardware.

Rusty bolts, tools and car parts can soak clean in Duda Energy Phosphoric, a food-grade acid sold at 85 percent strength. The seller says to cut it with water to somewhere between a quarter and half strength, and the bath leaves a thin phosphate coat that slows new rust. It's also a common way to etch bare metal before painting. Undiluted, it causes severe burns to skin and eyes, so mix it carefully and store it locked away.

Gray, weathered decks and rust streaks on wood are what oxalic acid does best, and Ecoxall Oxalic Acid sells it as a fine, nearly pure powder. Mixed with water, it lightens dark water marks and tannin stains on bare wood before refinishing, and it lifts rust from metal. It's poisonous if swallowed and can harm the kidneys, so keep it well away from food, kids and pets.

Big tiled patios, pool decks and masonry walls suit StoneTech Restore, a gallon of concentrate from Laticrete's stone-care line. The label gives mixing ratios for light, medium and heavy jobs, and it clears dirt, hard-water deposits, mineral bloom and rust from tile and acid-resistant stone. It's water-based and solvent-free, which helps indoors. The jug is pricey up front, and few home users have weighed in on it yet.