Misty And Murky, Why?

[fiona and my babies]

hello!!
iv been busy today, treated the fish to some new plants and a tube to swim through.
at the same time i have done a 30% water change, hovered out the gravel so it all looked nice.
but ever since the water is all misty and murky looking, its normally crystal clear, any idea why???
any idea will be great!!!

 

[CFC]

It sounds like a bacterial bloom, usually assosiated with a sudden rise in ammonia/nitrite and the bacteria multiplying rapidly to use it up. When you hoovered the gravel did you disturb much gunk in the gravel?