Is hydrogen peroxide a pool fix? DC Reflecting pool algae explained

Even after $16 million worth of renovations were completed on the Lincoln Memorial Reflecting Pool, the green algae first spotted over the weekend has remained.

The hydrogen peroxide poured into the pool from gallon jugs on Tuesday, it turns out, appears to have done little to stop the ​algae’s spread.

The liquid, which can be toxic if not used correctly, was dumped into the pool as a potential remedy to help return the pool to the “American flag blue” promised by ⁠President Donald Trump.

But is hydrogen peroxide safe for the pool - and will it help turn the iconic Washington DC tourist destination ‌back to the color envisioned by the president?

Here’s what ​we know.

Hydrogen peroxide is a natural bleach and is created with water and an extra oxygen molecule. That extra molecule, according to the Cleveland Clinic, kills bacteria and removes stains.

The hydrogen peroxide dumped into the reflecting pool was 12% concentrate, four ⁠times stronger than household peroxide.

Is hydrogen peroxide safe?

In short, the answer ‌is complicated.

Although the company Harris, which ‌makes the brand of hydrogen peroxide used in the reflecting pool, calls the concentrated formula “safe for use around people and pets when used as ⁠directed,” the Occupational Safety and Health Administration has still deemed it hazardous.

The 12% concentrate is significantly more hazardous than the standard household version.

If ingested, it could cause immediate and ‌painful burning of the digestive tract. It ‌can also cause serious chemical burns and tissue damage if touched, as well as hazards through its vapors or mists.

Is it safe to use hydrogen peroxide in a pool?

Yes, and ⁠it’s actually commonly used in pools.

“Unlike chlorine, which produces harmful disinfection byproducts ​like trihalomethanes and chloramines, hydrogen peroxide breaks ⁠down into ​just two things: water and oxygen,” Alliance Chemical says. “That means no chemical smell, no bleached swimsuits and no respiratory irritation for swimmers with sensitivities.”

Although the 12% concentrate used on the reflecting pool is stronger than household peroxide, it’s much lower than ⁠concentrations sometimes used for larger pool treatments.

Alliance Chemical recommends 12% for hot tubs and small spas, with 30% concentrate used for large pools and heavy shock treatment.

Will hydrogen peroxide fix the reflecting pool?

It ⁠could, but it’s going to take a lot of it.

“The usual dose for peroxide shock is 1 gallon used for every 10,000 gallons of pool water,” according to Lab Valley Essential Chemicals.

This would make shocking the 6.75-million-gallon pool with hydrogen peroxide ⁠a difficult challenge, not even taking into ‌account the 12% concentrate.

It’s unclear how much hydrogen peroxide was ​used in the ‌reflecting pool, but as of Wednesday afternoon it still appeared to be green from ​the Washington Monument live camera.