Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
You could do a water change, I would try to do it like this:
Work on as thorough a gravel vac as you can. you are rinsing the substrate again while it is inside the tank. Toward the end dig a bit of a hole in the substrate and remove the water as much as possible from under the substrate, too.
Then refill, and deliberately aim the hose all over the substrate. Stir and mix as much as possible, then drain the tank again. Another rinsing while it is in the tank.
Then, do the real fill:
Arrange the substrate into hills and valleys, add rocks and driftwood, and plant (mist the plants to keep them moist)
Put a plate or plastic bag over the substrate and allow the water to run in slowly and seep over the edge of the plate.
There may be some minor clouding, but as thorough as you can be with the rinsing followed by gently filling in a way that does not stir up the substrate is the best you can do about minimizing the cloudiness. It will likely be ready for you to put the fish back in, since you already have a cycled filter.
Then I would clean the filter. The cloudiness from before may have added a lot of silt to the filter. Rinse the media gently in water with a little dechlor so as not to kill or dislodge the bacteria.
Clean it again in a day or two in case it is picking up more cloudiness from the tank.
If it is too cloudy to add the fish, while you are waiting for the cloudiness to clear keep on feeding the bacteria just like you are doing the fishless cycle.