The scenes are graphic. Thick gloopy algae, like a blanket of vomited green slime, coats what once was an idyllic little body of water, even oozing onto surrounding rocks.

This gloop is what Dave McFadden of Carmel Valley calls “the dreaded enemy.”

“Lemme tell you about algae,” he says. “It’s grown by different bacteria. It grows fast. It can become toxic – poisonous! Most of it is pretty nasty. And it’s so unsightly.”

After studying landscape and “plantscape” architecture, McFadden worked for two decades building ponds for various clients. (His other life, he says, is “as a cowboy on a ranch.”) But all too often, once the pond was complete, the enemy would eventually advance.

Historically, property owners with ponds – including water features at the area’s ubiquitous golf courses – used algaecides, including chemicals like potassium permanganate and chlorine, to attack the algae. But it attacked the immune systems of local flora and fauna along with it. Sick fish and dead ducks suck. Beneficial bacteria was killed off too.

The alternative was super labor-intensive, demanding from McFadden a full day and several men to extract fish, drain the water feature, scoop the goop and refill it.

No longer.

Under the shingle Dave’s Amazing Pond & Turf, McFadden has introduced a new weapon. The inspiration for the name was simple: When clients saw how quickly it dissolved algae – it bubbles up, turns yellow and disappears in a matter of minutes – they tended to have one word for it.

The science is simple and slick. A proprietary mix, developed with the help of UC Santa Cruz chemist, delivers a stable and clear combination of citric and ascorbic acid, a natural steroid from the yucca plant and low levels of hydrogen peroxide (as higher levels would be unstable and hurt fish). The acids affix to the algae, the steroid helps break down the cell walls, and hydrogen from the algae and the acid recombines with the available hydrogen and oxygen of the hydrogen peroxide (H2O2) to form pure water (H2O).

McFadden’s patent is pending – and proves stunningly versatile. It also breaks down organic build-up, stains, moss, mold and mildew in the soil, in deeper root zones, along golf courses, turf grass and in water. It works in koi ponds, aquariums, waterfalls, creeks, streams and water fountains. Outdoor furniture, sidewalks, stones, slate, tile, fiberglass, wood, bathrooms and kitchens are all fair game. It deodorizes smelly refrigerators, grease traps and pet areas. The other day he used it on a parade of ants – and they haven’t returned.

Best of all, it attacks mosquito larvae which thrive in the same stinky, dirty, low-oxygen, high-pH water as does algae. He has already partnered with the Salinas Valley Mosquito Abatement District, and reports 100-percent efficacy in the waters he treated.

McFadden’s recent promotional efforts include what he calls “Show Us Your Aquatic Cleaning Challenge.” Locals within 25 miles of Monterey can visit davesamazing.com/contest and share a pic of a nasty pond, fountain, waterfall, creek, or stream and win a free cleaning. A winner gets hooked up every month through November.

By now, McFadden has built about 100 ponds and serviced hundreds more; his clients include Granite Construction and Carmel Valley Ranch.

Carmel Valley resident Nancy Kessler recently had McFadden transform a busted waterfall that didn’t allow for plant growth into a lush flow of water and foliage.

“He’s been doing this for so long that he’s just so knowledgable,” Kessler says. “I’m blown away how effective the treatment is.”

He’s looking forward to taking on a lake at Quail Lodge next, partly because so many people have faced the dreaded enemy there – and failed.

“It’ll be interesting for people who say it can’t be done,” he says.