I have had a problem w/greenish cloudy water for about 4 weeks now and I was told by people at the acquarium store where I do business that it is algae. My tank is 29 gal. and all of the sudden one day I noticed that it was getting cloudy. It is not by a window, but I do leave my tank light on for about 15 hours a day and so maybe that is why the algae started growing. I have two other smaller tanks and I have no problem with them and I don't do anything different w/my 29 gal. Anyway, I was told there is no permanent way to kill this algae. I put "Acurel F" in the tank and it clears for a couple of days and then gets cloudy again. I was told I could rent a filter unit from the acquarium store and that would clear the tank, but that it would be temporary. Is there really nothing out there that I can add to the water to kill this algae off? Today I have started to decreased the amount of time I leave the light on in the tank to about 10 hours a day. Maybe I'll go down to 8 hrs. I also was told that adding these 2 plants, "anacris" and "cabomba", to the tank may help kill the algae because the plants will be using the same nutrients that the algae needs and eventually the nutrients will run out and the algae will die. Does anyone believe this? The only other thing I can think of is emptying my tank and starting all over again, which I will do as a last resort. The acquarium store person also told me that there is stuff you can buy that claim to kill algae, but that they don't really work that well and also they leave bad things in the water (he didn't really say "things" but I forgot the word he used). Thanks for any help you can give me.