Not fertilising the plant, no - it's growing madly enough as it is! I can easily solve the sunlight problems by not opening the curtains in the morning until the sun has moved high enough. Thinking about it, that could be the problem as it's only recently started and summer is approaching, so the sun has been alot brighter and warmer in the mornings. Actually, don't remember the tank getting the morning sun when I first put it there, so I'm betting that's the prob. Combined with too many fish and my propensity to over-feed the little guys. I will try very hard to control myself

The lights are on for 10-12 hrs a day, but are pretty low wattage, and havent caused the prob before,
Thanks heaps guys, I'll get these fishies into their new home asap, cut down on food and keep the curtains closed a bit longer. Hopefully that will work.
Hehe...again, shawnie, your post wasnt there when i started typing. I think you may be on the money, but fortunately shouldnt have to move the tank. Glad you told me these chemicals could stuff up my tanks cycle - wouldnt have thought of that. Ta!