Yes, this is true but depends on what you have in your tank. I mean fish, plants, and beneficial bacteria and everything else. For freshwater its not as important as it is for saltwater. Freshwater is easier to get to a point that the system takes care of itself. Saltwater...ughh so hard. You'll have to add things to make it a self reliant system but eventually you'll get it. Nitrates, ammonia and nitrites are more important to monitor that your ph. Remember tho depends on what you have in your tank. With SA/CA its ph isn't that important. I'm gonna have to learn how to deal with ph. I'm just throwing that in for anybody that is just interested in reading about aquarium water for plant watering.