I started with a tennis ball sized piece of cheato and it has grown in 3-4 months to pretty much fill my fuge area of my sump. It is all still very green, and I just manually roll it over about twice a week so the bottom of the ball gets some light... but how soon do I need to trim it? I don't want to experience a mass die off or something and have a bunch of dead material make its way into the tank... that would kind of defeat the purpose of it in the first place .