Red tide returns to eastern beach

Clovelly Beach is again on red alert.

The beach in Sydney's east was closed on Wednesday morning because some red algae, known as Noctiluca scintillans or sea sparkle, remains in the water.

"The algae has dissipated somewhat overnight, probably due to rain and high tide this morning," a Randwick Council spokeswoman said. "But it's certainly still there, so as a precaution we'll be leaving the beach closed at this stage.

"The lifeguards are closely monitoring the situation."

Clovelly and Bondi were both closed on Tuesday after the red algae appeared.

The Metropolitan Sydney South Coast and Hunter Regional Algal Co-ordinating Committees attributed the algal bloom to an "upwelling of nutrient rich deep ocean water onto the continental shelf"', which was often seen after rainfall near river mouths.

It can be high in ammonia and can cause skin irritation.

Bondi reopened on Tuesday afternoon and a Waverley Council spokeswoman said the algae had not reappeared overnight.

"It's all clear, all good. The beach is open, the flags are up, it's all back to normal."