our 55 is green

[sara8]

we have a 55 gal with a couple sharks and 2 silver dollars in it. the tank has turned so green you can't see through it. when we first set up our 30 it went through a stage where it was really green but it cleared up on it's own. our 55 is filtered with a canister filter and only has a couple sticks of bamboo in it no other plants. it isn't in direct sunlight either. we are going to do a water change tonight but does anyone have any ideas about causes? it doesn't seem to be bothering my fish either.

[Ambieruns10]

Its probably just algae. What is the temp and how long do you leave your light on? Im not an expert though but those are the first two things I thought of.