Algae growing in my sand

[motownjc]

LFS gave me a chunk of chato said it had pods in it. Told me to just shake it in the take the pods will come out in the water. Now I have algae growing in my sand. How do I get rid of this?

 

[Madmanmadrid]

Holy blue hahaha. Do you have any daylight pics? That would help alot in Id what's in your sand.