Ken Sauer
Fish Fanatic
My daughter just bought a 3-gallon betta tank. She set the tank up and then used water from a well-cycled tank with excellent water parameters as the water in the new tank. Is the tank now cycled and ready for a fish? Thanks
Thanks so muchI'm afraid not. The beneficial bacteria don't live in the water column, they live attached to hard surfaces. In the filter medium, on the substrate, attached to tank walls and decor.
If she can pinch some filter media or substrate from a clean, well established tank, that can help jumpstart the cycle. Even moving a filter over isn't an instant cycle, since the bacterial colonies still need to grow and establish everywhere else in the tank, but it can speed the process up considerably.
Edit to add: I moved a whole, long established sponge filter over to a new tank when I had to set up a new tank as an emergency, but since all the substrate, plants etc were new, even with a very low bioload it still went through a mini-cycle of sorts as the bacteria grew everywhere else. Needed 75% daily water changes for a while, but within a week or so it stablised. So if she can get some filter media, or a good amount of substrate from an established tank, test the water daily and do water changes anytime ammonia or nitrites go above zero, or nitrates go above 20ppm.