So that means two things:

- 1 m³ of hot water is less water (in terms of mass) than 1 m³ of cold water

- 1 kg of hot water has a bigger surface area than 1 kg of cold water

I am still not convinced that this alone would explain such a phenomena. I'd rather believe there is some weird fluid dynamics and layering involved.

> such a phenomena

The singular is "phenomenon".

Thanks, English is not my first language.

it’s all greek to me!

Personally, I think it's still English!

por que no los dos?

The first seems compelling to me, less mass means less over all energy to freeze.

The second less so. Hot water has a bigger surface area, which makes heat loss fast at first. When it gets to cold water's temp it should have the same surface area as the cold water making the advantage disappear.