Algae comes back after 12 hours

[shadow_k]

Hey all
So yesterday I did a 20% water change on my 20 gallon tank , cleaned the walls rock sand etc.. not even 12 hours and I have all this algae back what could be the problem ?

 

[jgirardnrg]

Looks like Dino's

 

[shadow_k]

Ahh okay thank you !