A lab tech is analyzing water samples and notices that one of her samples is more green. What does this tell her about the sample?

Another cause for excess algae in the tank is dirty water. Algae grow rapidly when the nitrate levels in the water increase. To prevent this and to keep the tank clean, change 25 to 30 percent of the water on a frequent basis. Algae growth also accelerates with too much light. Move the aquarium away from direct sunlight, or keep the blinds or curtains drawn. If the aquarium has its own artificial light, limit the amount of time that it is kept switched on.