Hi, the water in my tank has turned green. I think it was caused by the charcoal i added to the filter, i have always added it with no problems but the brand i used this time was differnt and i didnt rinse it first. My oscars are still healthy and everything else is fine, i just dont know how to clear the water. I have been doing twice weekly water changes(of 10% - 20%)but it just isnt helping. Any suggestions would be greatly appreciated. It has been going on about three weeks now. Thank-you

Hey there snap, how are you doing and firstly welcome to the site....

So what size of tank do you have? What kinda of fish do you have in it and what filter?

How long has your tank been set up and most importantly can you post the results of your water. Ammonia, Nitrites, Nitrates and Ph?

Then we can get to the bottom of it..

hey, there and welcome.
If the greenness came at the same moment as you introduced the new media,
I guess not rinsing the charcoal will have released quite a bit of dust in your tank.
I don't think it will hurt your fish, it just looks bad.
You either can start doing bigger waterchanges or wait for your filters to take the dust out.
Extra polishing pads or cottonwool in your filter may help.

if green color came from the charcoal, it will clear up soon but
if you were hit gradually by green algae, it will progress as time
goes by. you need to reduce lights (sunlight enhance green algae),
increase the lateral volume of your media, and do 20 percent water
change daily.