The Lincoln Memorial Reflecting Pool has been turning green since the 1920s, and the reason is baked into its original design. The pool stretches roughly a third of a mile, sits one and a half to two and a half feet deep, holds about 6.5 million gallons, and was built on Washington D.C. marshland that has been slowly sinking ever since. Ravi Kurani brought in Terry Arko, Product Training and Content Manager at HASA Pool with over 45 years in the industry, to diagnose what is really going on and whether it can actually be fixed.
What we cover:
Still water is algae's best friend. The pool was intentionally designed to stay still to function as a mirror, which means strong surface circulation, the intervention that would help most, directly conflicts with the pool's purpose.
The 1920s design got the basics wrong. Built on unstable marshland with asphalt paving and no meaningful filtration, the ground shifted so badly that engineers later had to drive large timber beams beneath the basin to stop it from sinking. The pool has been leaking roughly 16 million gallons of water per year.
Nutrients have gotten worse over a century. Phosphates and nitrates in the Potomac watershed are significantly higher today than in the 1920s, driven by population growth, industrialized agriculture, and runoff, giving algae more fuel than it ever had.
Nanobubbles buy time, not a cure. Nanobubble ozone systems stay neutrally buoyant in the water column for days or weeks, and combined with hydrogen peroxide generate hydroxyl radicals that destroy a wide range of contaminants. Terry is skeptical the technology alone can fully solve the problem given the pool's underlying design constraints.
Chlorine still has no equal on green algae. After 45 years in the pool industry, Terry has not seen a more effective algaecide than chlorine for green algae. The challenge at the reflecting pool is the cost and logistics of daily liquid chlorine dosing at that scale, plus concerns about chloramine odor in a public monument setting.
Offline circulation could be the workaround. Terry's proposed fix is to route water through a high-flow filtration loop located off-site, then reintroduce it gently so the surface stays still, preserving the mirror effect while giving the water the turnover and treatment it needs.
Terry Arko is Product Training and Content Manager at HASA Pool, a manufacturer of liquid chlorine, liquid acid, and specialty pool chemicals, with over 45 years of experience across field service, chemical development, and water treatment formulations. Connect with Terry on LinkedIn:
Terry recommends "The Hidden Messages in Water" by Masaru Emoto (2005), which explores how environment and human behavior can affect the very structure of water, bridging the scientific and the personal.
Podden och tillhörande omslagsbild på den här sidan tillhör
Ravi Kurani. Innehållet i podden är skapat av Ravi Kurani och inte av,
eller tillsammans med, Poddtoppen.
