green water in a new aquarium

Question
got a 20gls tank. set it up 4 days ago in the same spot where i've had my 10gls for the last 8 years. the water of the 20 gls is totally green. no fish in there yet. a few real plants and some rocks. have not used excessive light, if anything not enough. not sure what to do next. should i change some of the water? vacuum the tank? have cleaned the filter several times to find this brown stuff all over it...never had this problem with the smaller aquarium.
how do i know what kind of algae i have. maybe is something else.
hope you can help.

maritza

Answer
Did you tank all the stuff from the old tank and put it in the new one?  If the water is green, it's an algae bloom and you could simply keep the tank lights off and cover the tank for 2-3 days to kill off the algae in the water. That's about the only thing I can think of to help.