vkcy:
I bought it from "bunnings warehouse" in Gardening section. I'm not sure where you can buy it in Hong Kong.
keisuke:
To be honest I don't know what the colour temperture is. they have warm white and cool white plus other different colours to choose. mine is cool white. as I know LED has very narrow spectrum. I was taking a risk to use LED light and I didn't know if they are suitable for aquatic plant growing. Luckily my plants growing quite well so far.
compare LED to fluorescent tube in lumen/watt, LED has slightly lower efficiency than f.tube. but LED consumes less power and produces less heat.