As it grows it uses up nitrates in the water and when you trim it, you are removing the nitrates from the tank. Most people put it in a their sump or refugeum as its quick growth can be a nuisance in the display tank. All you have to do is give it light and sit back while it grows, trimming along the way. Most people choose to use a reverse light cycle as the display tank to help keep ph frpm dropping at night.