Sun, algae and tote covers

Why a clear bottle goes green

Algae need light, warmth and nutrients. A clear or milky HDPE bottle lets light in, a full tote in July is warm, and any dust or leaf litter supplies nutrients. The result is a film on the walls, a tint in the water and a smell. Rain tote water is rarely clean to begin with, and sun speeds the change.

Covers that work

• A shade structure over the tote: a shade cloth on a frame.
• A tote cover or a wrap that blocks light.
• A dark paint on the cage side facing the sun, not on the bottle.
• Placement on the north or the shaded side of a building.
• A fence or hedge to break the afternoon sun.

Ultraviolet and the plastic

Sun does not only feed algae; it ages the polyethylene. A bottle that sits in full sun for years will chalk and weaken. Shade protects the water and the tote.

Cleaning a green tote

Drain it, rinse the bottle with a soft brush, never a wire one, and rinse again until the water runs clear. For a tote used on plants, a mild cleaner followed by a thorough rinse is enough. For drinking water, follow CDC guidance and replace the bottle if stains persist.

Choosing a spot

Walk the yard at three in the afternoon, when the sun is hardest, and note where shade falls. The north face of a building, the lee of a tree and the inside of a corner are good. Avoid south-facing walls, which reflect heat, and avoid tote positions over a drain or a septic field. A tote that sits in shade from noon onward will stay several degrees cooler through the summer.